Documentation

• 1: Quick start
• 2: SPL Sense
• 2.1: Installation and updates
• 2.2: User interface and search
• 2.3: Measurements
• 2.4: Measurement data
• 2.5: Value profiles
• 2.6: Live screen and kiosk
• 2.7: Leveler
• 2.8: Sensor and calibration
• 2.9: Autonomous mode
• 2.10: Settings
• 3: SPL Sense for Linux
• 3.1: Hardware and operating system
• 3.2: Installation
• 3.3: Update
• 3.4: Operation
• 4: SPL Cloud
• 4.1: Account and interface
• 4.2: Organizations and roles
• 4.3: SPL Sense instances
• 4.4: Jobs with several measuring points
• 4.5: Measurements in the cloud
• 4.6: Read access
• 5: SPL Cloud Pro
• 5.1: Pricing and billing
• 5.2: Shared links
• 5.3: Reports and pictures
• 5.4: Alarms
• 5.5: Remote control and comments
• 6: For developers
• 6.1: SPL Sense API
• 6.2: Data formats
• 7: Basics
• 7.1: Templates for V-NISSG and DIN 15905-5
• 7.2: Glossary
• 7.3: Measuring point and offset
• 7.4: Audience noise

1 - Quick start

This guide takes you step by step to your first measurement. No prior knowledge needed.

What you need:

• a computer running Windows or macOS
• an SPL Tools sensor with USB cable
• for SPL Cloud (step 8): internet and an email address

1. Install SPL Sense

1. Download SPL Sense for your operating system:
   • Windows
   • macOS with Apple chip (M1 and newer)
   • macOS with Intel processor
2. Open the downloaded file and follow the installer.
3. Start SPL Sense. On first start, a notice appears. Read it and click Accept and Continue.

SPL Sense updates itself: when a new version is available, a notice appears.

2. Connect the sensor

Connect the sensor via USB. Only one sensor may be connected per computer. The status bar at the top right shows whether SPL Sense detects the sensor.

If the status bar shows Sensor disconnected, unplug the cable and plug it in again.

3. Create a measurement

A measurement stands for one measuring point, for example “Main stage Openair 2026”. It can run over many days.

1. On the overview, click New measurement.
2. Fill in the fields:
   • Name: how the measurement appears in the overview and in the report.
   • Value Profile: defines which values are calculated and which limits apply. For events in Switzerland, choose the template that matches your reported category: VNISSG 93dBA, VNISSG 96dBA or VNISSG 100dBA. In Germany, choose DIN 15905-5. What the templates contain: Templates for V-NISSG and DIN 15905-5.
   • Day Boundary: when a measurement day ends. Choose a time about two hours after the end of the event, at the latest 06:00. This way a party lasting until 03:00 ends up in one day instead of two.
   • Cloud Uplink: leave it off for now. You switch it on once SPL Sense is connected to the cloud (step 8).
3. Click Create Measurement.

4. Activate the measurement

Only one measurement can be active at a time. The active measurement is the one SPL Sense records into.

Open the measurement and click Activate measurement.

5. Set the offset

The limit applies at the loudest place in the audience, at ear height. You usually can’t put the sensor there. That’s why you measure at a different place and compensate for the difference with the offset. Background: Measuring point and offset.

How to set the offset (the measurement must be active and stopped, the sensor connected):

1. In the Measurement menu, open Tune offsets.
2. Play pink noise through the sound system, as loud as during the event.
3. Click Reset max values.
4. Walk through the audience area with the sensor, including the front and the sides. SPL Sense remembers the highest value.
5. Place the sensor at its measuring position, for example at the mixing desk.
6. Set the Offset so that Level with applied offset is as high as the stored Max value.
7. Click Save.

Nothing is recorded while tuning offsets. If you already know the offset, for example from a handheld meter, enter it directly under Edit Measurement.

6. Measure

1. Click Start. SPL Sense is now recording. The first values appear after the first full minute.
2. Below the page title you see the current levels. The chart shows the course of the day.
3. For a large, easy-to-read display, for example for the DJ or the technicians, click Live Screen.
4. When the event is over, click Stop and confirm.

If the sensor is unplugged during the measurement, SPL Sense shows Interrupted. When you plug it in again, the measurement continues by itself.

7. Edit the measurement

You can change name, day boundary, offsets and value profile later, as long as the measurement is stopped: Measurement menu › Edit Measurement, make the changes and Save.

If you change the value profile or the day boundary, SPL Sense recalculates the limits and measurement days.

8. Connect to SPL Cloud

In SPL Cloud your measurements are safely archived. You can see them on the go and share them with others. The basic features are free.

Create an account (once):

1. Open spl.cloud in your browser.
2. Click Sign up now, enter your email address and click Send verification code.
3. Enter the code you receive by email and confirm.
4. Add your password and name and finish with Create.

Register SPL Sense (once per computer):

1. In SPL Sense: Settings › Cloud › Register instance.
2. Click the link shown or scan the QR code with your phone. The code is only valid for a short time; if it has expired, request a new one with Get new code.
3. In SPL Cloud: under Owner, choose who this computer belongs to: you personally or an organization you are a member of. Click Save.
4. SPL Sense now shows Instance is registred.

Upload the measurement to the cloud:

1. Open the measurement in SPL Sense, Measurement menu › Edit Measurement.
2. Switch on Cloud Uplink and save.

SPL Sense now uploads all data of the measurement, including what was already recorded. If the internet connection drops, SPL Sense keeps measuring and catches up with the upload later. In SPL Cloud, the measurement appears on the overview under the independent measurements.

9. Download a PDF report

For every measurement day, SPL Sense offers a day report as PDF.

1. Open the measurement in SPL Sense.
2. Select the day.
3. Click PDF next to the day.

With CSV next to it, you export the values of the day, for example for Excel.

In SPL Cloud, the day report is available with SPL Cloud Pro.

What next?

• When the event is completely over, complete the measurement: Measurement menu › Complete measurement. After that it can no longer be changed. You can re-open it if needed.
• Measuring point and offset: measuring correctly according to V-NISSG and DIN 15905-5
• Read access: give the organizer or the authority insight
• Leveler: keep the level below the limit automatically

2 - SPL Sense

SPL Sense is the measurement software for the sensor. It records the sound level, displays it live, rates it against your value profile and, if required, controls the volume with the leveler. SPL Sense works without internet; with SPL Cloud the data is additionally archived online.

This chapter is aimed at professionals. For your first measurement, the Quick start is enough.

2.1 - Installation and updates

Platforms

The features are the same everywhere. The only exception: you can calibrate the sensor only in the desktop app.

Installation

Open the downloaded file and follow the installer. To find out which Mac you have, go to Apple menu › About This Mac: “Chip” means Apple chip, “Processor” means Intel.

First start

On first start, SPL Sense shows a privacy notice. Accept and Continue proceeds, Close Application closes SPL Sense.

Updates

SPL Sense checks by itself whether a new version is available. If so, the notice Update available appears on the overview with the buttons Update and Remind me later.

1. Stop a running measurement. No update can be installed during a measurement.
2. Click Update and then Update and restart.
3. SPL Sense downloads the new version, installs it and restarts.

If SPL Sense does not restart by itself after the update, start it manually. After a restart, no measurement is active unless autonomous mode is switched on.

The current version and the version history are under Settings › About.

Where the data is stored

SPL Sense stores all measurements locally on the computer:

Back up this folder regularly or switch on the Cloud Uplink for your measurements. You back up individual measurements as .splsense files, see Import and export.

2.2 - User interface and search

Status bar

The status bar is at the top of every page:

• Logo and path: the logo leads to the overview, the path next to it back to higher-level pages.
• Device status: shows at a glance what is happening:
  • Measurement running (green, with the current LAeq 1 s): a click opens the live screen.
  • Measurement stopped or Sensor disconnected (red): a click opens the active measurement.
  • No measurement loaded
• Connected devices: sensor, leveler and cloud connection, each with its state. If remote control from SPL Cloud is allowed, this is shown here too.
• Search (magnifying glass), Help (question mark, opens this documentation) and Settings (gear).

Overview

The overview lists all open measurements as cards. Each card shows the state of the measurement and the values of the last four measurement days, coloured according to the thresholds of the value profile. Below are the completed measurements as a short list.

At the top right, New measurement creates a measurement and Import restores a backed-up measurement.

At the bottom of the overview you find the connected sensor, a connected leveler and, if available, a notice about an update.

Measurement page

• Page header: name, state and the most important actions as buttons, for example Start or Stop. All other actions are in the Measurement menu. Actions that change the measurement permanently (Deactivate, Complete) are at the end of the menu.
• Live strip: while measuring, you see the 1-second values and, if active, the leveler below the page header.
• Days and chart: select a measurement day; the chart shows its course. Next to the day you find the buttons PDF (day report) and CSV.
• Below: deviations, events, sensor and cloud uplink.

What the values and markers mean is described under Measurement data.

States of a measurement

More under Measurements.

Search

Open the search with the magnifying glass or with Ctrl+K (Mac: ⌘+K). It finds measurements (open and completed), settings pages, value profiles and live screens. Use the arrow keys to select a result and Enter to open it.

You can also find settings by keywords, for example “password” for the operator PIN or “limiter” for the leveler.

Use on tablet and phone

In web server mode (Linux) you operate SPL Sense in the browser, also from a tablet or phone. The interface adapts to small screens: the path in the status bar becomes a back link, lists are shown one below the other.

2.3 - Measurements

A measurement stands for one measuring point. It contains its settings (value profile, day boundary, offsets, leveler) and all recorded data. A measurement can run over many days and be started and stopped as often as you like.

Flow

create / import
        │
        ▼
     open ──activate──▶ active ──Start──▶ running ──Stop──▶ active (stopped)
        ▲                  │                │ sensor gone   ▲
        │             deactivate            ▼               │ sensor back
        └──────────────────┘           interrupted ─────────┘
        │
    complete ──▶ completed ──re-open──▶ open

• Activate: at most one measurement is active at any time; SPL Sense records only into it. You can only switch when the active measurement is stopped.
• Start and stop: Start needs a connected sensor. Stop asks for confirmation. If the leveler is active, SPL Sense points out that it will be switched off when stopping.
• Interrupted: if the sensor is unplugged or delivers no values for 20 seconds (for example because the computer was asleep), the measurement is interrupted. When the sensor delivers data again, it continues by itself. You end an interrupted measurement with Stop.
• Deactivate: Measurement menu › Deactivate. The measurement remains open but is no longer active.
• Restart of SPL Sense: after a restart, no measurement is active. If a measurement should continue automatically, use autonomous mode.

Create

On the overview, New measurement:

A new measurement is not yet active. Its leveler is set to SPL Tools L1 (USB) and mode Off.

Edit

Measurement menu › Edit Measurement. Possible as long as the measurement is not running, not interrupted and not completed. You can also edit a measurement that is not active while another one is recording.

• Name, Day Boundary
• Cloud Uplink: switching it on uploads all data of the measurement, including what was already recorded. Switching it off stops the upload; what is already in the cloud stays there.
• Offsets for A, C and Z, see below
• Value Profile: adjust it with Edit Value Profile

If you change the day boundary or value profile, SPL Sense recalculates the limits and measurement days. Every change of the offsets and of the value profile appears in the events.

You edit the leveler settings separately; they can also be changed during the measurement.

Offsets

The offset converts the values at the measuring position to the loudest place in the audience. How to determine it is described under Measuring point and offset.

There are two ways:

• Tune offsets (Measurement menu): with live values. Only for the active, stopped measurement with a connected sensor. The table shows, per weighting, the current level, the highest level since Reset max values, the offset and both values including the offset. Nothing measured here is recorded.
• Edit Measurement: enter offsets directly as numbers, for example from a measurement with a handheld meter.

A changed offset applies from the next start. Data already recorded keeps the offset it was recorded with.

Complete and re-open

When the event is over, complete the measurement: Measurement menu › Complete measurement. The measurement must be stopped. After that it is locked: it can no longer be activated, edited or started, but it can be viewed and exported. If autonomous mode is set to this measurement, it is switched off.

You re-open a completed measurement in the menu with Re-open measurement.

Deleting

You delete an open measurement under Edit Measurement › Delete measurement, a completed one in the Measurement menu. It is only deleted on this computer; what is in SPL Cloud stays there. How to delete the measurement in the cloud as well is described under Measurements in the cloud.

Import and export

A measurement can be backed up as an .splsense file and read in again on another computer, with all data and settings.

• Export: complete the measurement and click Export measurement.
• Import: on the overview, Import, then drag the file into the field. If the measurement already exists, you can replace it with Overwrite existing measurement.

You export the values as a table in CSV format, see Measurement data.

2.4 - Measurement data

The measurement page looks the same in SPL Sense and in SPL Cloud. What is described here applies to both; differences in the reports are listed at the end.

Measurement days and chart

The data is organized by measurement days; a measurement day ends at the measurement’s day boundary. Each day shows the values of the value profile, coloured according to the thresholds: yellow for Notification, orange for Warning, red for Limit. Show all days displays older days.

The chart shows the course of the selected day:

• the values of the value profile as lines, the rating as a coloured band
• comments and events as markers
• excluded time ranges greyed out
• with an active leveler, also the signal level (line), the gain reduction and the correlation

The first values appear after the first full minute of recording.

Interval details

A click into the chart opens the details of the minute at that point (an interval): all values, the spectrum in third-octave bands and the check results. Use the arrows to move to the previous or next minute.

Deviations

The Deviations section lists, per value of the value profile, when the selected day exceeded a threshold, with the highest value. A click on an entry draws the thresholds into the chart.

Events

The Events section lists everything that happened with the measurement, newest first:

• recording started and stopped, with reason (for example manually, autonomous mode, microphone disconnected, sleep mode, sensor reconnected)
• measurement created, activated, completed, re-opened
• offsets, value profile and leveler settings changed, each with the old and new values
• leveler bypassed and re-enabled
• comments and changed excluded time ranges

If a change came via SPL Cloud or the API, this is indicated; for the cloud, also by whom.

Comments

With Add › Add comment in the Events section you record something at a point in time, for example “Encore” or “Offset checked with handheld meter”. Comments appear in the chart and can be edited later. For a completed measurement, comments are only possible up to the time of completion.

Excluding time ranges

Some periods should not be included in the rating, for example tuning the system with pink noise before doors open. With Add › Exclude a time range you define such a range with From, To and a comment.

An excluded range:

• is greyed out in the chart and marked Not counted
• does not count for maxima, the rating according to the value profile and the deviations
• is kept with all measurement data

Count again? removes the exclusion. Every change appears in the events.

Reports and exports

In SPL Cloud, the day report (also with deviations) and a pictures report are available with Pro.

Cloud uplink

If the cloud uplink is switched on, the measurement page shows the upload status: Online, Offline and how many intervals, events and leveler statistics are still waiting for upload. Without internet, SPL Sense keeps measuring normally and catches up with the upload.

2.5 - Value profiles

A value profile defines which values a measurement calculates and from when they count as too loud. It determines the colours on the overview and in the chart, the deviations and the alarms in SPL Cloud.

Structure

A value profile consists of one or more values. Each value has:

Examples: Leq, A, 60 minutes gives LAeq 60′; MaxF, C, 1 minute gives LCFmax 1′.

Averages are calculated as moving averages: LAeq 60′ is, at every minute, the average over the preceding 60 minutes, also across the day boundary and across pauses. A value counts as above the threshold if it exceeds it; exactly equal is still fine.

Built-in templates

SPL Sense provides templates for Switzerland (V-NISSG) and Germany (DIN 15905-5). The values are listed under Templates for V-NISSG and DIN 15905-5. Built-in templates cannot be changed.

Your own templates

Under Settings › Value Profiles › Create you create your own templates:

1. Enter a Name.
2. Add the values you need with Add Value and set the thresholds.
3. Click Save.

You can change or delete your own templates at any time. Measurements that use a template are not affected: the template is copied into the measurement when it is created.

Changing the value profile of a measurement

Measurement menu › Edit Measurement › Edit Value Profile. Here you choose another template or adjust the values directly. If the profile differs from its template, SPL Sense indicates this; Reset profile to template values restores the template’s values.

When saving, SPL Sense recalculates all previous measurement days with the new profile. The measurement data itself does not change. The change appears in the events with the old and new profile.

2.6 - Live screen and kiosk

The Live Screen shows the current values large and easy to read, for example on a second display for the DJ or the technicians. You open it on the measurement page with Live Screen or by clicking the device status in the status bar.

Choosing a screen

Choose the screen at the top right of the live screen. SPL Sense remembers per measurement which one was used last.

Screens for common cases are built in, each with and without leveler display:

Custom screens

Under Settings › Live Screens › Create:

1. Enter a Name.
2. Add widgets with Add.
3. Arrange them on the grid: drag a widget to move it and its corner to resize it. With the keyboard: arrow keys move, Shift + arrow keys resize.
4. Select a widget to change its type or set its Color Thresholds.
5. Save.

The preview shows placeholder values at real size, so you can see how large the numbers will be. On narrow screens the widgets are stacked.

Widgets

Color thresholds

Numeric widgets change colour when a value exceeds a threshold. You set the thresholds manually or take them from the measurement with From value profile. This only works for times above one minute, because the value profile knows no shorter times.

Full screen and kiosk

Full screen switches the live screen to kiosk mode: instead of menus, a slim bar shows only measurement, screen, time of the last value and device status. The widgets fill the whole screen, even on a large TV. Leave full screen returns.

If an operator PIN is set, SPL Sense asks for it when leaving the live screen and full screen. This way nobody at the DJ booth can change the settings.

For devices that should start directly into the live screen, see SPL Sense for Linux › Operation.

2.7 - Leveler

The leveler automatically keeps the level below a limit. SPL Sense measures the sound level with the sensor, receives from the leveler device the level of the signal it is currently outputting (line level), and calculates how much the volume must be reduced (gain reduction). The leveler device applies the reduction in the signal path.

The leveler belongs to the measurement: each measurement has its own leveler settings. You find them in the Measurement menu › Leveler Settings.

Variants

For Q-SYS there is the plugin SPL Sense Leveler: download. Add it to your Q-SYS design and enter the IP address of the computer running SPL Sense, the port and the API key in the plugin. In SPL Sense, under Settings › API, the mode External Leveler Only or Full Control must be switched on, see SPL Sense API. If the settings are correct, the plugin shows the state and the measured values of SPL Sense.

SPL Tools L1 via USB

Connect the L1 via USB. In the measurement’s leveler settings, Leveler Connection then shows Connected with type, serial number and firmware.

SPL Tools L1 via network

1. Choose SPL Tools L1 (network).
2. Enter the name or IP address of the L1 under Host, or click Search: SPL Sense then looks for L1 devices on the local network.
3. Enter the API Key of the L1.
4. Choose the Security:
   • HTTP (L1 TLS off): unencrypted, only in protected local networks
   • HTTPS, pinned certificate: encrypted with the L1’s own certificate. Read the fingerprint with Read from L1 and compare it with the one shown on the L1.
   • HTTPS, trusted CA: encrypted with a certificate from a recognized authority
5. Click Test connection and then Save.

The easiest way is Set up from L1 on USB: plug the L1 in via USB once, and SPL Sense takes over host, API key, security and fingerprint. If the L1 has no API key yet, SPL Sense generates one.

After several wrong API keys, the L1 blocks the connection for 30 seconds.

Setting up the L1 itself

When an L1 is connected via USB, you set it up under Settings › Leveler:

• Device Information: type, serial number, firmware, MAC addresses
• Ethernet Configuration: automatic or static with IP address, netmask and gateway
• WiFi Configuration: network and password. The L1 only supports 2.4 GHz networks. The status shows the connection and signal strength.
• Network API: hostname, API key (empty: leveling over the network off; Generate creates one), admin password for the L1’s web interface and the encryption (Off, Self-signed certificate, Custom certificate)

Limits and mode do not belong here but in the measurement’s leveler settings.

Modes

Background on audience compensation: Audience noise.

Limits

Under Limit Values you enter a limit between 40 and 140 dB for each of A, C and Z. An empty field means: this weighting is not controlled. If several limits are set, the weighting that requires the greatest reduction applies; it is called dominant.

The leveler controls to an average over about 10 seconds. The gain reduction is at most 40 dB.

Calibrating the line offset

Only for the mode with audience compensation. The line offset is the difference between the level at the sensor and the line level when only the sound system is playing. Before calibrating, the measurement must be active and stopped, the sensor connected and the leveler mode saved or applied (Apply settings).

1. Play pink noise through the entire signal chain, as loud as during the event. If a DJ mixer is the source, feed the noise into the DJ mixer.
2. Make sure it is quiet: no audience, no conversations, no other sources.
3. Click Capture Line Offset. SPL Sense measures for three seconds and enters the line offset for A, C and Z.
4. Check the Correlation: it should be as close as possible to 1.000 for all weightings. Otherwise repeat the measurement.
5. Save.

You can also change the line offset manually. Be careful: even a small deviation causes the leveler to ignore audience noise or to intervene too strongly.

Reading the correlation

The correlation compares the measured level with the level the sound system alone should produce.

During the measurement

When the measurement is running and the leveler is active, the live strip shows:

• the current Gain Reduction
• the Correlation per weighting; the dominant one is bold and marked with >, for example > 0.987 @A
• the 1-second level of the dominant weighting highlighted

You can change limits, mode and line offsets during the measurement as well; they apply immediately without the gain reduction jumping. Calibrating is only possible with the measurement stopped.

The day chart additionally shows the line level, the gain reduction and the correlation. With the cloud uplink, this data also goes to SPL Cloud.

Warnings

Bypass

Bypass Leveler switches the control off immediately, for example in case of a problem. Caution: the volume then rises by the current gain reduction. With 15 dB reduction, it suddenly gets 15 dB louder.

The bypass applies to the whole device and stays on until you lift it with Reenable Leveler, even across a restart, a change of measurement or unplugging and replugging. As long as it is active, the overview and the measurement page show a notice.

Stop and interruption

• Stop: the leveler sets the gain reduction to 0 and releases control. SPL Sense warns when stopping if the leveler is currently reducing.
• Interrupted (sensor gone): the last gain reduction remains until the sensor delivers data again.

Who can change what

The leveler settings can be changed for every open measurement, even without a sensor and even when it is not active. Not for a completed measurement. From SPL Cloud, mode, limits and line offsets can be changed via remote control, but not the connection or the calibration.

2.8 - Sensor and calibration

Sensor information

Under Settings › Sensor Information (or by clicking the sensor on the overview) you see:

• Device Information: serial number, hardware revision, MCU ID, firmware version, quality check
• Voltage and MCU Temperature, refreshed with Refresh measured values
• Calibration: date, by whom, valid until
• Weather Protection: the compensation filter that is set

Always connect only one sensor to a computer running SPL Sense. If you change the sensor during a measurement (unplug, plug in another), SPL Sense continues measuring with the new one; the affected minute is marked in the data.

Calibration status

If the calibration has expired or is invalid, SPL Sense asks for confirmation when starting the measurement (Start anyway). If the measurement is started via autonomous mode, the API or remote control, SPL Sense does not ask.

Weather protection filter

A weather protection over the microphone slightly changes the frequency response. The compensation filter corrects this. It must match the weather protection used:

• Enable Filter for SPL Tools W1 for the SPL Tools W1 weather protection
• Enable Filter for Weather Protection V1 for the older V1 weather protection
• Disable Filter without weather protection

The filter is stored in the sensor and applies until you change it, also for other measurements and on other computers. You can only change it when no measurement is running. When it is switched on, the overview shows a notice and the measurement data is marked.

Calibrating the sensor

With an authorization as a calibrator, you can calibrate sensors yourself. You need:

• SPL Sense for Windows or macOS (not available in web server mode)
• internet
• a sound calibrator with 94 or 114 dB
• a confirmation as a calibrator from SPL Tools (see below)

Applying as a calibrator

1. On the sensor page, Calibrate › Apply as Calibrator.
2. Fill in the online form. In it, you also describe your calibration equipment.
3. SPL Tools reviews your application and confirms it by email.

As soon as you have the confirmation, you can calibrate.

Procedure

The measurement must be stopped and the sensor connected.

1. Sensor page › Calibrate › Log In. SPL Sense shows who you are logged in as and the current calibration.

2. Put the running calibrator on the sensor and wait until the level is stable.

3. Click the capture button for 94 dB or 114 dB, matching your calibrator.

4. Check the Capture Result:

   • Capture drift: fluctuation during the capture
   • Previous calibration drift: how far the sensor deviates since the last calibration

   If the values indicate that the sensor is drifting, SPL Sense warns you. Calibrate again and check the sensor for mechanical damage; if in doubt, send it in for inspection.

5. Choose the Signing Organization and the certificate, and fill in Calibrated For and Calibrator Device.

6. Click Sign and Store Calibration.

The calibration is digitally signed and stored in the sensor. From now on, the measurement data is signed with the new calibration.

A sensor without a previous calibration cannot be calibrated this way. In that case, contact SPL Tools.

2.9 - Autonomous mode

In autonomous mode, SPL Sense activates and starts a specific measurement by itself as soon as SPL Sense starts. This is intended for permanently installed systems, for example in a club or on a Raspberry Pi: after a power failure or restart, the system continues measuring without intervention.

Setup

1. Settings › Autonomous Mode.
2. Set Automatically run a measurement when running to On.
3. Choose the Measurement. Only open measurements are offered.
4. Save. If SPL Sense is stopped and a sensor is connected, SPL Sense offers to start the measurement right away.

Behaviour

• When SPL Sense starts: the chosen measurement is activated and started. If no sensor is connected, the measurement is Interrupted and starts recording as soon as the sensor is there.
• Stopping: you can stop the measurement at any time. It then stays stopped until SPL Sense starts the next time.
• Completing: when the measurement is completed, autonomous mode switches itself off.
• Calibration: with the automatic start, SPL Sense does not ask, even if the calibration has expired. The events show the reason Automatically started as autonomous measurement.

For unattended operation

Combine autonomous mode with:

• an operator PIN, so that nobody changes the settings
• the live screen in kiosk mode as a display
• the cloud uplink, so you can see the measurement remotely, and with Pro alarms in case the measurement fails

2.10 - Settings

Open the settings with the gear at the top right. Each row shows the current state.

Operator PIN

An operator PIN protects SPL Sense against changes. Without a PIN, anyone with access to SPL Sense can change everything.

1. Settings › Operator PIN.
2. Enter a New PIN (4 to 8 digits) and repeat it.
3. Save.

With a PIN set:

• all pages except the live screen are locked. SPL Sense shows SPL Sense is locked and asks for the PIN.
• SPL Sense also asks for the PIN when leaving the live screen and full screen.
• the PIN applies in the app and in the browser (web server mode).

Remove PIN lifts the protection again.

SPL Cloud

Under Settings › Cloud you connect SPL Sense with SPL Cloud. A registered installation is called an instance in the cloud.

Registering

1. Register instance. SPL Sense needs internet for this.
2. Open the link shown or scan the QR code with another device. The code is only valid for a short time; Get new code gives you a new one.
3. Log in to SPL Cloud and confirm the registration. Choose the Owner: you personally or an organization you are a member of. See Organizations.

The page then shows Instance is registred with instance ID, host, owner and the connection status (Online, Connecting…, Offline).

Which measurements go to the cloud is set per measurement with the Cloud Uplink, see Measurements.

Unregistering

Unregister Instance disconnects SPL Sense from the cloud. The cloud uplink is switched off for all measurements; what is already in the cloud stays there. After registering again, you switch the uplink back on per measurement.

If the page shows Authentication failed!, unregister the instance and register it again.

Allowing remote control

With Allow remote control, people with access to this instance in SPL Cloud may start and stop, switch and create measurements and change offsets, leveler and value profile, as long as SPL Sense is online. Calibration and updates are never possible remotely.

Remote control is off by default. When it is on, the status bar shows this, and every command from the cloud appears as a message and in the measurement’s events, with the name of the person.

In the cloud, remote control requires SPL Cloud Pro on the measurement.

API

The SPL Sense API lets you monitor and control SPL Sense and connect external audio processors as levelers. It is off by default. Details under SPL Sense API.

Language

German, English, French or System Default.

About

Version, release notes (English), contact, privacy policy and the open source licenses used.

3 - SPL Sense for Linux

On Linux, SPL Sense runs without its own window as a web server in the background. You operate it in the browser, on the device itself or from another computer, tablet or phone in the same network. This suits permanent measuring stations, for example a Raspberry Pi in a club or in a rack.

You are basically free in your choice of hardware; an ARM architecture (32 or 64 bit) is required. This guide describes the Raspberry Pi.

1. Hardware and operating system: what you need and how to prepare the Raspberry Pi
2. Installation: install SPL Sense and set it up as a service
3. Update
4. Operation: access, kiosk display and unattended operation

If you are familiar with Linux, SSH and the command line, you can go straight to the installation.

Except for calibrating the sensor, SPL Sense on Linux can do everything it can do on Windows and macOS.

3.1 - Hardware and operating system

Hardware

You can buy the Raspberry Pi from electronics retailers. We have tested:

• Raspberry Pi 4 or 5, Model B (all memory variants)
• for power over the network cable: the official Power-over-Ethernet module (PoE HAT) for the Raspberry Pi 3B+ and 4B

Memory card

The memory card is the part most likely to fail after many operating hours. SPL Sense writes little, but a high-quality micro SD card is still worth it. We have had good experiences with “SanDisk Extreme Pro”.

Size is hardly an issue: Raspberry Pi OS with desktop fits on 8 GB, and even a lot of measurement data needs barely a gigabyte. We recommend at least 16 GB.

Installing the operating system

1. Install the Raspberry Pi Imager on your computer (available on the Raspberry Pi website).
2. Use it to write Raspberry Pi OS with Desktop to the memory card.
   • Choose 32 or 64 bit. For a Raspberry Pi 5 we recommend 64 bit. Remember your choice: you need the matching package when installing SPL Sense.
   • In the Imager settings, set a user name and password, and switch on SSH if you want to set up the Raspberry Pi from another computer.

If you are experienced with the command line and don’t need a screen on the Raspberry Pi, Raspberry Pi OS Lite without desktop is enough. This guide assumes the desktop variant.

Assembling

1. Install the Raspberry Pi with the desired add-on modules in the case and insert the memory card.
2. Connect screen, keyboard and mouse.
3. Connect power (or the network cable with PoE). The Raspberry Pi starts.
4. On first start, set up a network connection, by cable or Wi-Fi. SPL Sense is downloaded from the internet in the next step.
5. If not already switched on in the Imager: enable SSH under Raspberry menu › Preferences › Raspberry Pi Configuration › Interfaces.
6. Note the IP address of the Raspberry Pi: it appears when you hover the mouse over the network icon at the top right.

3.2 - Installation

SPL Sense is installed via the command line, either directly on the Raspberry Pi (program Terminal) or via SSH from another computer. With SSH you can copy and paste the commands and avoid typing errors.

Connecting via SSH

Your computer must be in the same network as the Raspberry Pi.

• macOS and Linux: in the terminal ssh <user>@<ip-address>, for example ssh pi@192.168.10.144
• Windows: in the terminal (PowerShell) also ssh <user>@<ip-address>, or with PuTTY: enter the IP address under Host Name, set Connection type to SSH, then Open

User and password are the ones you set in the Raspberry Pi Imager.

General notes

• Linux is case-sensitive. Copy the commands exactly.
• A successful command usually shows no message. If an error message appears, read it and fix the error before you continue.
• At the first sudo, the Raspberry Pi asks for your user’s password.

1. Create a user for SPL Sense

sudo useradd splsense -m -d /opt/splsense-data

SPL Sense runs under this dedicated user and stores its data in /opt/splsense-data.

2. Download and unpack SPL Sense

For a 32-bit operating system:

wget https://r.spl.swiss/dl/splsense/linux-arm -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

For a 64-bit operating system:

wget https://r.spl.swiss/dl/splsense/linux-arm64 -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

3. Move the program to its place

sudo mv splsense /usr/local
sudo chown splsense /usr/local/splsense -R
sudo chgrp splsense /usr/local/splsense -R

4. Set up the service

So that SPL Sense starts automatically at boot, set it up as a system service. Open a new file in the nano editor:

sudo nano /etc/systemd/system/splsense.service

Copy this content into it:

[Unit]
Description=SPL Sense
After=network-online.target
User=splsense
Group=splsense

[Service]
Type=simple
ExecStart=/usr/local/splsense/SplSense.App.Browser
WorkingDirectory=/usr/local/splsense
Environment="ASPNETCORE_URLS=http://0.0.0.0:8080"
Environment="SPLSENSE_DATA=/opt/splsense-data"

[Install]
WantedBy=multi-user.target

Save and close: Ctrl+X, then confirm with Y.

The ASPNETCORE_URLS line defines the address and port at which SPL Sense can be reached: here 8080 on all network interfaces. Enter a different port here if needed. Without this line, SPL Sense can only be reached on the Raspberry Pi itself (http://localhost:5000).

5. Enable and start the service

sudo systemctl enable splsense
sudo service splsense start

6. Restart

sudo reboot

Done

SPL Sense now starts automatically at every boot and runs in the background. In the browser of the Raspberry Pi or of another device in the network, open the IP address with the port, for example http://192.168.10.144:8080.

From here it works as on any other platform, for example with the quick start. For operation as a permanent measuring station, see Operation.

3.3 - Update

Automatically

On Linux, SPL Sense updates itself like on the other platforms: when a new version is available, Update available appears on the overview. Stop the measurement and click Update and Update and restart. See Installation and updates.

This works if SPL Sense is set up as described in the installation.

Manually

If the automatic update fails, update via the command line. Connect to the Raspberry Pi as in the installation. The general notes apply here too.

1. Stop SPL Sense

sudo service splsense stop

2. Download and unpack the new version

32 bit:

wget https://r.spl.swiss/dl/splsense/linux-arm -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

64 bit:

wget https://r.spl.swiss/dl/splsense/linux-arm64 -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

3. Replace the old version

sudo rm -rf /usr/local/splsense
sudo mv splsense /usr/local
sudo chown splsense /usr/local/splsense -R
sudo chgrp splsense /usr/local/splsense -R

The measurement data is in /opt/splsense-data and is kept.

4. Start and restart

sudo service splsense start
sudo reboot

3.4 - Operation

Addresses

With port 8080 from the installation:

On the Raspberry Pi itself, you can use localhost instead of the IP address.

Kiosk display

For a permanent display, for example a screen at the DJ booth, the browser opens the live screen directly in kiosk mode, for example with Chromium:

chromium-browser --kiosk "http://localhost:8080/measurement/live?kiosk"

Kiosk mode only shows the widgets and a narrow status bar and adapts to the screen size. See Live screen and kiosk.

Unattended permanent measuring station

1. Switch on autonomous mode: the measurement starts by itself after every restart, for example after a power failure.
2. Set an operator PIN: without the PIN, only the live screen is accessible, also in the browser of other devices.
3. Connect to SPL Cloud and switch on the cloud uplink.
4. Optionally with Pro: alarms on failure and remote control.

Limitation

You cannot calibrate the sensor on Linux. For that you need SPL Sense for Windows or macOS.

4 - SPL Cloud

SPL Cloud at spl.cloud archives the measurements from SPL Sense and makes them available in the browser, from anywhere and for everyone you give access to. It runs in parallel to SPL Sense: measuring always happens locally, and the cloud receives the data continuously as soon as internet is available.

Everything in this chapter is free, except where Pro is noted. Additional features such as day reports, alarms, remote control or shareable links are available per measurement with SPL Cloud Pro.

This chapter is aimed at professionals. To get started, the quick start is enough.

4.1 - Account and interface

Account

You create an account on spl.cloud with your email address, as described in the quick start. An account is personal: create one for each person and work as a team with organizations instead of sharing one account.

Profile

Settings › My Profile › Edit Profile:

• First Name, Last Name, Display Name (how others see you)
• Company Name and address
• Phone: for SMS alarms. The national format also works (079 …); the cloud converts it to the international format.

Language

Settings › Language: Browser Default, German, German (Switzerland), English or French.

Status bar

• SPL Sense instances: for example “SPL Sense 3 of 5 online”. A click shows all your instances with their state, current activity and, while measuring, the LAeq 1 s. Instances that lost their connection during a measurement are marked red. See SPL Sense instances.
• Search (magnifier), Help (question mark) and Settings (gear)

Overview

The overview shows Jobs and Measurements:

• Jobs with their measurements
• Independent Measurements: measurements that are not assigned to a job. A new measurement from SPL Sense appears here first.
• at the bottom, the list of your SPL Sense instances

Each measurement shows its state and the values of the last days, coloured according to the thresholds of the value profile. If a measurement is activated with Pro, this is shown.

Create new job creates a job.

Archive

Ten days after its end date, a job moves to the Archive; before that, the overview shows in how many days this will happen. You reach the archive via Previous jobs and measurements at the bottom of the overview. Archived jobs and measurements are kept in full.

Search

With the magnifier or Ctrl+K (Mac: ⌘+K) you search measurements, jobs, instances, organizations and settings. Archived entries are listed last and marked. You can also find instances by their operating system, for example “mac” or “linux”. The search only shows what you are allowed to open.

Live data

Pages with running measurements update themselves. If the connection drops, the cloud shows Connection to SPL Cloud lost and reconnects; Reconnect now does it immediately.

4.2 - Organizations and roles

Why organizations?

Everything in SPL Cloud has an owner: measurements, jobs and SPL Sense instances. The owner is either a person or an organization.

An organization is a group of people who access measurements together: a company, a club, a festival or an authority. All members see the organization’s measurements, and when someone leaves the company, the data stays with the organization.

A person can be a member of several organizations, for example as a freelance technician working for several companies. When creating a job or registering an instance, you choose who should own it.

Roles

An organization always has at least one owner.

Anyone who should only view data, for example an organizer or an authority, does not become a member but gets read access.

Creating an organization

1. Settings › Create Organization.
2. Enter Name, address and E-Mail Address. The Billing language determines the language of invoices and payment pages.
3. Save. You are now the owner of the organization.

Managing members

On the organization’s page:

1. Add Member.
2. Search for the person by email address. They must already have an SPL Cloud account.
3. Choose the Role: Owner or Member. Save.

Clicking a member opens it: change the role or Remove Member.

Logo

The organization’s logo appears in the PDF reports of its measurements. Upload logo (image file up to 5 MB), Change logo or Remove logo.

Typical setups

Individual: a technician with her own sensor and laptop, without an organization. Instance and measurements belong to her personally. She gives the organizer read access to the measurement.

Technical company: the company has an organization; all laptops and Raspberry Pis are registered as instances of the organization. All employees are members and see all measurements. At a festival, a job groups the measuring points; the authority gets read access to the whole job, the operator of a stage to their measurement.

Rented devices: if a device is rented out and should belong to the renting company for the rental period, change the owner of the instance, see SPL Sense instances.

4.3 - SPL Sense instances

Every installation of SPL Sense that is registered with SPL Cloud is called an instance: a laptop, a desktop PC or a Raspberry Pi. How to register an instance is described under SPL Sense › Settings.

States

Where to find instances

• Status bar: “SPL Sense 3 of 5 online”, with a list of all your instances
• Overview, at the very bottom: all instances with state, activity, owner and current level
• Settings › Personal Sense Instances and on the page of each organization

Each instance shows the icon of its operating system (Apple, Windows, Linux).

Instance page

Clicking an instance shows:

• what it is doing: during a measurement, the running measurement with the current 1-second values, with an active leveler also gain reduction and correlation; when offline, the last contact
• the Details: Instance ID, host, operating system, owner, registration date
• with Pro, remote control

Who owns the data

A new measurement uploaded by an instance belongs to the owner of the instance. Only instances of the same owner may upload into an existing measurement.

Changing the owner

You change the owner of an instance by registering it again:

1. In SPL Sense: Settings › Cloud › Unregister Instance.
2. Register instance and, when confirming in the cloud, choose the new Owner.
3. In SPL Sense, switch on the Cloud Uplink for new measurements.

The instance keeps its ID. Measurements that have already been uploaded keep their previous owner. The instance can no longer upload into them, because only instances of a measurement’s owner may upload into it. So change the owner between two assignments, not during a running measurement.

Removing an instance

On the instance page, in the menu: Unregister Instance. The instance can then no longer upload anything. The measurements in the cloud are kept. Also unregister the instance in SPL Sense so that it stops trying to connect.

4.4 - Jobs with several measuring points

A job groups several measurements that belong together: all stages of a festival, the measuring points of a construction site or a club with a main and a side room. Each measuring point remains a separate measurement with its own sensor, value profile and data. The job shows them together and lets you set access, Pro and alarms for all of them at once.

Jobs only exist in SPL Cloud; SPL Sense only knows measurements.

Creating a job

1. On the overview, Create new job.
2. Name, for example “Openair 2026”.
3. Location (optional).
4. From and To: the period. It determines when the job moves to the archive, namely ten days after the end date.
5. Owner: you personally or an organization. The owner cannot be changed later.
6. Save.

Assigning measurements

On the job page, in the menu Job › Manage Measurements:

• Assign Measurements: choose measurements that do not yet belong to a job.
• Remove takes a measurement out of the job. It becomes independent again.

Finish Manage Measurements ends editing.

Each measurement belongs to at most one job.

Different owners

Job and measurements can belong to different owners. Typical case: the organizer keeps the job “Openair 2026” in their organization, and a technical company measures a stage with its own laptop. The measurement then belongs to the technical company (the owner of the instance that uploads it), the job to the organizer.

Assigning

Only someone who may do both can assign a measurement: manage the job and manage the measurement. In practice, this is a person who is a member of both organizations. The measurement keeps its owner when assigned.

Who may do what

In the example, A is the technical company (owner of the measurement) and B the organizer (owner of the job).

“A” and “B” each stand for the person or all members of the organization that owns the measurement or job.

Pro with different owners

• If B activates Pro for the job, B pays for all measurements in it, including A’s, in B’s currency.
• If A has already activated Pro directly on the measurement, that stays: A continues to pay for this measurement.
• If A deactivates the direct activation while the job is Pro, the measurement stays Pro via the job.

See also Pricing and billing.

Editing and deleting

Edit changes name, location and period. Delete Job is only possible when no measurements are assigned to it anymore.

Example: festival with three measuring points

A technical company looks after a festival with a main stage, a tent and a measuring point at the nearest residential building.

1. Three laptops with SPL Sense are registered as instances of the company’s organization.
2. On each laptop, a measurement with cloud uplink is created: “Main stage”, “Tent”, “Neighbourhood”.
3. In the cloud, the job “Openair 2026” is created with the festival period, and the three measurements are assigned.
4. The authority gets read access to the whole job, the operator of the tent only to their measurement.
5. Optionally: Pro for the whole job, for example for alarms to the technicians or a shared link for the organizer.

4.5 - Measurements in the cloud

A measurement appears in SPL Cloud as soon as its Cloud Uplink is switched on in SPL Sense and the instance has internet. New measurements are listed first under the independent measurements on the overview.

The measurement page

Below the title, a line shows the essentials: job, owner, the instance currently measuring (with state), and whether Pro is active.

• Live: while the measurement is running, you see the current 1-second values, with an active leveler also gain reduction and correlation. If the instance stops reporting, Connection lost is shown with the last contact.
• Days, chart, deviations and events: the same as in SPL Sense, see Evaluating measurement data.
• On the side: access (who sees the measurement), Pro, pictures and the other measurements of the same job.

If something about the measurement changes in SPL Sense, for example the offset, the page updates itself.

Reports and exports

The reports carry the logo of the organization that owns the measurement.

Completing

Menu Measurement › Complete measurement. After that, the cloud no longer accepts new data, even if SPL Sense keeps measuring. Data up to the time of completion that is still on its way still arrives.

If you complete the measurement in SPL Sense, it is also completed in the cloud. It is reopened in SPL Sense or with remote control.

Deleting

You delete a completed measurement in the menu Measurement › Delete measurement. It is permanently removed from the cloud. The measurement is kept in SPL Sense.

Who sees the measurement

4.6 - Read access

With read access, another person sees a measurement or a whole job without being able to change anything. Typical for organizers, operators or authorities.

There are two kinds:

This page describes the free read access.

Granting read access

1. Open the measurement or the job.
2. Menu Measurement or Job › Manage Read Access.
3. Add Read Access.
4. Search for the person by email address. They must have an SPL Cloud account; if not, ask them to create one.
5. Select scope: only this measurement or the whole job. Access to the job also applies to measurements added later.
6. Save.

The Read Access Users list shows who has access, since when and who granted it. Remove revokes it.

Anyone who may manage the measurement can grant read access: the owner, or all members of the organization that owns it.

What readers see

People with read access find the measurement on their overview. They see all data, days, events and pictures and can download CSV exports, and with Pro also day reports. They cannot change anything, pass on access, or complete or delete the measurement.

5 - SPL Cloud Pro

The basic SPL Cloud is free. With Pro you extend individual measurements with additional features, without a subscription and without a contract. Billing is per measurement and measuring day.

What Pro costs and how it is billed is described under Pricing and billing. Read that page before activating Pro for the first time.

5.1 - Pricing and billing

The principle

• Pro applies per measurement. You activate it for a single measurement or for all measurements of a job.
• You pay per measuring day. A measuring day counts if the measurement recorded more than one hour of data on that day. The measurement’s day boundary is decisive.
• There is a cap per measurement and year. Once reached, Pro continues free of charge until the end of the measuring year.
• No subscription, no base fee. A measurement without data costs nothing.

Prices

You find the current prices on spl.swiss. The model:

• The first measuring days of a measurement cost more; from the 7th measuring day, a lower daily price applies.
• There is a cap per measurement and measuring year. Once reached, Pro continues free of charge until the end of the measuring year.
• The measuring year lasts 365 days from the measurement’s first measuring day (if it has no data yet: from the day of activation). After that, a new measuring year begins and counting starts again at the first day.
• Prices exclude VAT.

Before each activation, SPL Cloud shows the price and, if data has already been recorded, the exact amount. If prices change, a measurement that is already activated keeps the price at the time of its activation.

Prerequisite: payment method

Before you activate Pro, the owner of the measurement needs a payment method and a billing address. The billing address is needed for VAT.

For Pro on a job, the owner of the job needs the payment method.

1. Choose the Billing currency: CHF or EUR. It cannot be changed afterwards.
2. Click Set up payment. Payment is handled by the payment service Stripe; there you choose the payment method and enter the billing address. You can see there which payment methods are available.
3. Back in SPL Cloud, Payment method and billing address saved. is shown.

The invoice is addressed to the person or organization that owns the payment method. Manage billing opens your invoices at Stripe and lets you change the payment method. For an organization, the Billing language in the organization details determines the language of the invoices.

Activating Pro

For a measurement

1. Open the measurement. On the side, Get Pro! shows the included features and the price.
2. Click Activate Pro and confirm.

For a job

On the job page, Activate Pro for the job. All measurements of the job are then Pro, including those added later. Each measurement is still billed individually by its measuring days, with its own cap.

The owner of the job pays, also for measurements that belong to someone else. Measurements for which their owner has already activated Pro directly continue to be paid by that owner. Details under Different owners.

Free test hour

The first time you activate a measurement directly, you have one hour to try it out. There is no test hour when activating via the job. If you deactivate Pro within that hour, it costs nothing, not even for days already recorded. While the test hour is running, the measurement shows Free test hour running.

Retroactive billing

Pro is billed from the measurement’s first measuring day, not from the time of activation. If you activate Pro for a measurement that has been running for three days, those three days count. SPL Cloud shows you the exact amount before activation.

Deactivating Pro

With Deactivate Pro on the measurement or Deactivate Pro for the job on the job:

• The Pro features are locked immediately. Shared links stop working, alarms are no longer evaluated.
• Amounts already accrued are billed with the next invoice. There is no refund.
• Further measuring days are no longer counted. The measurement continues recording normally.
• Measurements that were activated directly stay active when you deactivate Pro for the job.

Activating again

If you activate Pro again later, the measuring year continues seamlessly as if there had been no break. Measuring days from the break are counted retroactively. There is no test hour anymore; billing starts immediately. Switching off and on repeatedly therefore saves nothing.

Billing

Billing happens once a month, on the last day of the calendar month, for all measuring days accrued in that month. The stored payment method is charged automatically.

If the charge fails, the payment service retries several times. If payment fails definitively, the Pro features of the affected measurements are locked until the payment is settled.

Keeping an eye on costs

• Accrued costs in the payment settings: all Pro measurements with their costs in the current year.
• License details of a measurement (via View details at Pro): measuring year, billable measuring days, progress towards the cap, amounts already billed, billing history and all measuring days with their recorded time.
• License details of a job: total across all its measurements.

Only people who may manage the job or measurement see the costs.

5.2 - Shared links

With a shared link, anyone who has the link sees a measurement or a whole job, without an SPL Cloud account. Typical for organizers, operators and authorities, or as a QR code in a festival’s production office.

For people with an account, there is the free read access.

Prerequisite

• Link to a measurement: the measurement needs Pro.
• Link to a job: the job needs Pro (Activate Pro for the job). Pro on individual measurements of the job is not enough for this.

Creating a link

1. Menu Measurement or Job › Manage Read Access.
2. Under Read Access Links: Add Access Link.
3. Select scope: this measurement or the whole job.
4. Expiration: the date from which the link stops working. Leave empty if it should not expire. We recommend a date about ten days after the event.
5. Save.

You then see the link and the QR code. Copy copies the link, for example for an email. You can print the QR code.

What recipients see

Recipients open the link in the browser and see the measurement or job with all data, days, events and pictures. They can download day reports and CSV exports. They cannot change anything and only see what the link shares.

Revoking a link

Manage Read Access lists all links with their expiration. Remove invalidates a link immediately.

When Pro ends

If Pro is deactivated or payment fails, the links stop working. Recipients then see This shared link is currently not available. The links remain stored and work again as soon as Pro is active again.

5.3 - Reports and pictures

Day reports

In SPL Sense, the day report as PDF is free. In SPL Cloud it is available with Pro, in two variants:

• Day report: PDF button at the selected day. Without Pro, the button is greyed out.
• Day report with deviations: menu Measurement › Open day report with deviations. Additionally contains the exceedances of the value profile thresholds for the selected day.

If the measurement belongs to an organization with a logo, the logo appears in the report. You set the logo on the organization page.

Pictures for the measurement

Pictures document how the measurement was made: the measuring location, the sensor, the sound system, the record of the calibration run.

1. Open the measurement. On the side is the Pictures area.
2. Drag photos into the area or click +.
3. Clicking a picture opens it large. There you add a Caption and Save.

Anyone who sees the measurement sees the pictures, also via read access and shared links. Only people who may manage the measurement can add pictures, and only with Pro. Deleting (Delete picture?) removes the picture permanently.

Pictures report

Menu Measurement › Open pictures report creates a PDF with all pictures of the measurement and their captions. Together with the day report, this gives complete documentation of the measurement.

5.4 - Alarms

SPL Cloud checks the running Pro measurements every minute and notifies the registered recipients:

• Exceedance: a value is above a threshold of the measurement’s value profile.
• Downtime: a running measurement stops sending data, for example because power or internet is gone.

Alarms only run for measurements with Pro. Other measurements in the same scope are skipped.

Where to set up alarms

• For a whole job: menu Job › Alarms. The setting applies to all its measurements.
• For a single measurement: menu Measurement › Alarm configuration. For an independent measurement, this is the only way. If the measurement belongs to a job, this setting overrides the job’s setting for this one measurement.

At the top of the page you choose the scope: Full Job or Single Measurement. The list below shows the affected measurements and points out measurements without Pro or without limits.

Settings

First switch on Enable alarms for this scope.

Exceedance

• Trigger at severity: which thresholds of the value profile trigger an alarm: Notification, Warning, Limit. The thresholds themselves come from each measurement’s value profile. Without thresholds in the value profile, there are no exceedance alarms.
• Sustained for: the number of minutes the value must stay above the threshold before an alarm is triggered. This filters out short peaks. Default: 15 minutes; 5 to 15 minutes are common.

Downtime

• Silence before alarm: the number of minutes data may be missing before a downtime alarm is triggered. Default: 30 minutes. Devices on mobile networks often upload in bursts; don’t choose too short a time for them.

End of an alarm

Also notify when an alarm clears: a second message as soon as the level is normal again or data arrives again. Off by default, because it roughly doubles the number of messages. Leave it off if recipients get SMS.

Recipients

Recipients don’t need an SPL Cloud account. With Add recipient you enter per person:

• Email and/or Phone. SMS needs a phone number. The national format also works (079 …); it is converted to the international format.
• Receives: All alarms, Downtime only or Limit alarms only. Whoever brings a device back online rarely needs exceedances, and whoever monitors levels rarely needs downtime alarms.

It’s quicker with Add me and Add organization members: name, email and, if stored in the profile, the phone number are taken over.

When notifications are sent

• Exceedance: when the first severity is reached and again at every change of severity (for example from Warning to Limit or back). As long as the severity stays the same, no further message is sent.
• Downtime: once, when the downtime is detected.
• Several alarms in the same minute are combined into one message.
• The message contains a link to the measurement or job in SPL Cloud.

5.5 - Remote control and comments

With remote control, you operate SPL Sense from SPL Cloud, for example a Raspberry Pi in a rack or a laptop at another stage.

Prerequisites

• Allowed in SPL Sense: Settings › Cloud › Allow remote control. Off by default. This way the person on site always decides whether their instance may be remote controlled.
• Instance online: commands only go to a connected instance. There is no queue.
• Pro on the measurement: only measurements with Pro can be controlled.
• Permission: the owner of the instance; for an instance of an organization, all members. People with read access or a shared link can never control.
• SPL Sense version 2.0 or later.

What is possible

On the instance or measurement page, in the Remote control area:

Measurements on the instance shows all measurements of SPL Sense, including those without cloud uplink. Only measurements that are in the cloud and have Pro can be controlled.

What is not possible

• Calibration and software updates
• Measuring the line offset (needs noise and silence on site)
• Setting up the leveler connection
• Editing custom limits in the value profile; this is only possible on the instance

Confirmation and feedback

Every command that changes something asks first, with measurement and instance in the text, for example “Stop measurement ‘Main stage’ on ‘Laptop-FOH’?”.

After that, the cloud reports the result. If the instance doesn’t answer in time, the message says that the command may have been executed anyway; check the state of the instance in that case.

In SPL Sense, every command from the cloud appears as a message, and the measurement’s events show who triggered it (remotely by …).

If people on site and in the cloud change something at the same time, the last change wins.

Comments and excluded time ranges

With Pro, you can also add comments and exclude time ranges in the cloud in the Events area, just as in SPL Sense. This also goes via remote control: the instance must be online and allow remote control.

6 - For developers

Short and technical, for anyone connecting SPL Sense to their own software or hardware.

• SPL Sense API: local HTTP API for querying, controlling and as a leveler interface
• Data formats: CSV and .splsense

6.1 - SPL Sense API

Enabling

Settings › API in SPL Sense:

The page shows the base URL, the Swagger UI and the OpenAPI specification:

The API listens on all network interfaces, unencrypted (HTTP). Only operate it in trusted networks.

Connections to an SPL Tools L1 are not affected by this setting.

Authentication

Every request needs the API key, as the header

X-Api-Key: <api key>

or as HTTP Basic Auth (any user name, password = API key). Without a valid key: 401. If an endpoint is not allowed in the selected mode: 403.

Endpoints

The exact data structures are in the Swagger UI.

Controlling: POST /api/control

{ "action": "start" }

Response: { "success": true, "errorMessage": null }. The same rules apply as in the user interface; a start via the API does not ask about an expired calibration. The measurement’s events show via API.

Leveler settings: POST /api/leveler/settings

{
  "measurementId": "…",
  "mode": 30,
  "limitValueDbA": 96,
  "limitValueDbC": null,
  "limitValueDbZ": null
}

mode: 0 off, 10 simple leveler, 20 with panic function, 30 with panic function and audience compensation. Limits 40–140 dB or null (weighting not controlled). The line offsets remain unchanged. Not possible for completed measurements (409).

Leveler interface: POST /api/leveler

For audio processors that work as a leveler (for example with the Q-SYS plugin). The measurement must have the connection External audio processor (SenseAPI) in its leveler settings.

The processor calls the endpoint regularly (typically once per second) and sends its current output level:

{
  "lineLevels": [ { "levelA": -18.2, "levelC": -12.5, "levelZ": -10.1 } ],
  "externalLevelerType": "MyProcessor",
  "externalLevelerVersion": "1.0"
}

Line levels in dBFS (negative), each weighting optional. Several values are averaged energetically. Each call is one control cycle.

Response:

{
  "state": 20,
  "gainReduction": -3.5,
  "headroomBeforeGainReduction": 0,
  "dominantWeighting": "A",
  "compensatedRelevantSplA": 96.2,
  "compensatedRelevantSplC": null,
  "compensatedRelevantSplZ": null,
  "lineCorrelationA": 1.012,
  "lineCorrelationC": null,
  "lineCorrelationZ": null
}

gainReduction in dB, always ≤ 0. The processor applies this value as gain.

6.2 - Data formats

CSV

The CSV export is available per day and for the whole measurement, in SPL Sense and in SPL Cloud (there for the whole measurement as ZIP).

• Separator: semicolon ;
• one row per minute (interval)
• first column Timestamp: end of the interval in ISO 8601 format with time zone, for example 2026-07-12T22:15:00.0000000+02:00
• then one column per value of the value profile, in its order, with name and unit in the header
• values in dB with one decimal place, including offset
• decimal separator according to the user interface language

Excluded time ranges, comments and events are not included in the CSV.

.splsense

A .splsense file contains a whole measurement from SPL Sense with all recordings, signed intervals, events and settings. It is used for backup and for transfer to another computer (Import and export).

The format is internal and may change with new versions. For evaluation in your own software, use the CSV export and the SPL Sense API.

7 - Basics

These pages explain the terms and relationships you need for SPL Sense and SPL Cloud. They do not replace specialist literature. In Switzerland, the V-NISSG ordinance and the enforcement guide of the Federal Office of Public Health (BAG/FOPH) apply; in Germany, DIN 15905-5. Which templates SPL Sense provides for them is described under Templates for V-NISSG and DIN 15905-5.

7.1 - Templates for V-NISSG and DIN 15905-5

SPL Sense provides value profiles and live screens for the V-NISSG (Switzerland) and DIN 15905-5 (Germany). Which requirements apply to your event is set out in the original documents (below).

Value profiles

The values can be adjusted per measurement, see Value profiles. The matching live screens have the same names as the templates, each also in a variant with leveler display.

SPL Sense calculates averages such as LAeq 30′ or LAeq 60′ every minute as a moving average over the last 30 or 60 minutes. The value on the full and half hour equals the average over the past half hour, i.e. the 30-minute block of DIN 15905-5. If LAeq 30′ stays below the limit at all times, all blocks are met as well.

For the peak level, the DIN 15905-5 template uses LCFmax 1′: the highest C-weighted Fast value (125 ms) within one minute.

Original documents

• Swiss Federal Office of Public Health (BAG/FOPH): Vollzugshilfe zur V-NISSG, Schall (enforcement guide) and Messverfahren zur Ermittlung von Schallpegeln an Veranstaltungen (measurement procedure), on the FOPH website
• DIN 15905-5:2022-07, Event technology – Sound engineering – Part 5: Measures to prevent the risk of hearing loss of the audience by high sound exposure of electroacoustic sound systems

7.2 - Glossary

Measured values and notation

SPL Sense and SPL Cloud write measured values as is common in acoustics:

The letter after the L is the frequency weighting (A, C or Z), followed by the type (eq or Fmax) and then the time. A prime ′ stands for minutes. The unit is always dB.

CSV exports and PDF reports partly still use an older notation for the same values.

Terms A–Z

A, C and Z weighting

Filters that weight the frequency spectrum. A roughly corresponds to human hearing at low levels and strongly attenuates bass; the equivalent levels of the V-NISSG and of DIN 15905-5 are given in dB(A). C attenuates bass only slightly and shows how much low-frequency energy is involved; DIN 15905-5 uses it to limit the peak level. Z is unfiltered (zero). SPL Sense always measures all three.

Assessment level (Lr)

Term from DIN 15905-5: the LAeq over 30 minutes at the immission location, in blocks starting at every full and half hour. The permissible value is 99 dB.

Audience noise, extraneous noise

DIN 15905-5 calls everything that does not come from the sound system Störschall (extraneous noise), for example audience or pyrotechnics. See Audience noise.

Calibration

Adjustment of the sensor against a reference sound level. It has an expiry date. See Sensor and calibration.

Correlation

For the leveler, the ratio between measured and expected level. 1.000 means: only the sound system can be heard. Values above 1 indicate additional noise, for example from the audience.

Day boundary

Time at which a measurement day ends: between midnight and 06:00.

Deviation, exceedance

A value has exceeded a threshold of the value profile. The measurement details show them per day.

Excluded time range

A period that does not count for maxima, rating and deviations, for example the system tuning. The data is kept and shown greyed out.

Fast (F)

Time weighting of 125 ms. Reacts quickly to peaks. Basis for LAFmax.

Gain reduction (GR)

How many dB the leveler is currently reducing the volume by. Always 0 or negative.

Instance

An installation of SPL Sense registered with SPL Cloud, for example a laptop or a Raspberry Pi.

Interval

A recorded section of one minute. It contains all values of that minute and is digitally signed.

Job

Groups several measurements in SPL Cloud, for example all measuring points of a festival.

LAFmax, MaxF

The highest level with time weighting Fast within the chosen time. The V-NISSG limits LAFmax to 125 dB(A).

LCpeak

C-weighted peak sound pressure level: the highest instantaneous value of the sound pressure, without time weighting. DIN 15905-5 limits it to 135 dB. Not the same as LCFmax: there, the level is first smoothed with the time weighting Fast (125 ms), and the highest of these values is taken. Short peaks therefore come out lower; LCpeak is always equal to or higher than LCFmax.

Leq (equivalent continuous level)

The energy average of the level over a given time. A short, very loud moment raises the Leq considerably; a quiet moment lowers it only slightly.

Leveler

Automatically controls the volume of the sound system so that the limit is met.

Line offset

For the leveler with audience compensation: the difference between the level at the sensor and the signal level at the output of the audio processor, measured without audience.

Live screen

Large display of the current values, for example for the DJ or the technicians. Layout freely configurable.

Loudest place, immission location

The loudest place in the audience area, at ear height. This is where the limit applies. The V-NISSG calls it Ermittlungsort. DIN 15905-5 calls it maßgeblicher Immissionsort (relevant immission location) and distinguishes one for LAeq (determined by mid and high frequencies) and one for the peak level (determined by the bass). See Measuring point and offset.

Measurement

A measuring point with its settings and all recorded data. Can run over many days.

Measurement day

A day of a measurement, delimited by the day boundary. The Pro billing also counts measurement days.

Measuring position, substitute immission location

Where the sensor actually stands, for example at the mixing desk. DIN 15905-5 calls it Ersatzimmissionsort (substitute immission location).

Offset, correction value

Value in dB added to each measured value to infer the level at the loudest place from the measuring position. One value each for A, C and Z. In DIN 15905-5 they are called correction values KA and KC.

Operator PIN

Protects SPL Sense against changes. The live screen remains accessible without PIN.

Organization

A company, a venue or a festival in SPL Cloud. It owns measurements, jobs and instances; several people work together in it.

Pink noise

Test signal with equal energy per octave. Used to determine the offset and line offset.

Read access

Allows another person to view a measurement or a job in SPL Cloud without changing anything.

Recovery zone

Area where the audience can recover from the noise (Ausgleichszone). The V-NISSG requires it for events with an hourly level above 96 dB(A) that last longer than three hours.

Signature

Every interval is digitally signed. This makes it possible to prove that the data has not been changed.

Spectrum, third-octave band

The level split by frequency, in third-octave bands. Visible in the interval details and on the live screen.

Value profile

Defines which values a measurement calculates (e.g. LAeq 60′, LAFmax 1′) and which thresholds apply. Each value has up to three levels: Notification, Warning and Limit. See Value profiles.

Weather protection filter

Compensates for the effect of a weather protection on the microphone. Must match the weather protection used.

7.3 - Measuring point and offset

Loudest place and measuring position

The limits apply at the loudest place in the audience area. The V-NISSG calls it Ermittlungsort (at ear height), DIN 15905-5 calls it maßgeblicher Immissionsort. The sensor can rarely stand there during an event: in the middle of the audience it would be at risk, and shouting and applause would distort the measurement.

That’s why you measure at another place, the measuring position (DIN: Ersatzimmissionsort). The offset (DIN: correction value) compensates for the difference between the two places. SPL Sense adds it to every measured value so that the displayed and stored values correspond to the level at the loudest place in the audience.

Choosing the measuring position

• The sensor should receive the direct sound of the sound system: clear line of sight to the loudspeakers, not behind pillars, tent poles or the roof of the mixing desk.
• As little audience and other noise sources nearby as possible.
• Not in room corners and not directly against walls.
• Outdoors with weather protection, and switch on the matching weather protection filter.
• Do not move it during the event. If you have to move it, determine the offset again.

Distance to the loudspeakers

The sensor needs a minimum distance to the sound system:

• Only at some distance do the high, mid and low frequency drivers combine into the sound the audience hears. Too close to a loudspeaker, the sensor mainly measures a single loudspeaker, and the offset no longer holds for music.
• The sensor has a maximum level. Too close to a loudspeaker, peaks can overload it. SPL Sense shows this as Clip in the measurement data.

Within these limits: the farther the measuring position is from the audience and the better it lies in the direct sound of the sound system, the less audience and other sources interfere. If the measuring position is closer to the sound system than the loudest place in the audience, the offset becomes negative. DIN 15905-5 recommends such a measuring position.

Determining the offset

The offset is determined before the event with pink noise, as loud as during operation and through exactly the sound system that will play during the event. In SPL Sense this is done with Tune Offsets, described step by step in the Quick start. In short:

1. Play pink noise at operating volume.
2. Walk through the audience area with the sensor. SPL Sense remembers the highest level, this is your loudest place.
3. Place the sensor at the measuring position and set the offset so that the level at the measuring position plus the offset equals the highest level.

Alternatively, measure the level at the loudest place with a handheld meter and enter the difference directly under Edit Measurement. DIN 15905-5 requires a measuring duration of at least 15 seconds for this.

The offset applies per weighting: there is a separate value for A, C and Z.

• A (for LAeq and LAFmax): the loudest place is determined by the mid and high frequency drivers.
• C (for LCFmax and the peak level): the loudest place is determined by the bass and may be somewhere else. DIN 15905-5 allows the C offset to be determined from the LCeq; this is more reliable than using peak values.

Function test and calibration

For mobile measuring systems, DIN 15905-5 requires a function test with a calibrator before and after each event. The industry recommendation on the measurement procedure for the V-NISSG also recommends calibration before and after each measurement for mobile systems; the enforcement guide itself does not require organizers to calibrate. SPL Sense shows the calibration status of the sensor and warns before the start if it has expired. See Sensor and calibration.

Documentation

Record in writing how you measured.

• V-NISSG: at least the loudest place, the offset and the method you used to determine the offset.
• DIN 15905-5: a measurement report including organizer, date and place, start and end of the measurement, assessment levels and peak levels, measuring and calibration devices, result of the function test, location of the immission locations and the measuring position with justification, and the correction values and how they were determined. The complete list is in the standard, section “Messprotokoll”.

The measured values are provided, for example, by the PDF day report.

SPL Sense helps: every change of the offset automatically appears in the events, and with comments you record special circumstances directly in the measurement. In SPL Cloud you can also attach pictures of the measuring position to the measurement (SPL Cloud Pro).

Original documents: see Templates for V-NISSG and DIN 15905-5.

7.4 - Audience noise

What counts towards the level?

The regulations differ here:

• V-NISSG (Switzerland): everything that can be heard at the loudest place counts: sound system, stage, instruments and also the audience (industry recommendation on the measurement procedure).
• DIN 15905-5 (Germany): only the sound of the sound system is assessed. Audience and other sources are Störschall (extraneous noise) and should not distort the result. That’s why the standard recommends a measuring position where the audience hardly matters.

In both cases, the SPL Sense recording contains the total level at the sensor. No setting removes the audience from the stored measured values. How much it counts is therefore determined by your choice of measuring position.

The audience has little influence on the hourly level at most events (V-NISSG enforcement guide). For short periods, however, it can contribute significantly to the level: applause, chanting, singing along, loud stage monitors or rain on a tent roof.

What you can do

• Choose the measuring position well: if the sensor is above head height, away from the crowd and in the direct sound of the sound system, the audience has less effect. Keep enough distance to the loudspeakers. See Measuring point and offset.
• Keep the stage level low: loud monitors and backline increase the level without the technicians at the mixing desk being able to do much about it.
• Add comments: record special moments in the measurement, for example “Encore, audience singing along”. Comments appear in the day chart and help explain peaks later.

Leveler with audience compensation

The leveler automatically turns the sound system down when it gets too loud. Without further information, it would also do so when the audience is loud, making the music unnecessarily quieter even though the sound system is not to blame.

In the mode Leveler with panic and audience compensation, SPL Sense compares the measured level with the signal the audio processor is currently outputting. If it is louder than the sound system alone can explain (correlation above 1), the leveler only takes the share of the sound system into account. The measurement itself still records the full level.

For this to work, the leveler needs an accurately calibrated line offset. How to do this is described under Leveler.