Sarooma RTmeter · for Android (IOS follows)
Measure the reverberation time.
In under 60 seconds.
All you need is your smartphone,
a microphone, and a Bluetooth speaker.
RTmeter turns your mobile device into a room acoustics meter: T20 / T30 in octave bands from 125 Hz to 8 kHz – validated against Class 2 reference systems.
No spam—just a message as soon as RTmeter is available.
Validated by the HfT Stuttgart · Presented at DAGA 2025
IT’S THAT EASY
Three Steps to a Complete Measurement
01 · CONNECT
Pairing Hardware
Connect an external, omnidirectional microphone and pair speakers via Bluetooth – with impulse response, you don’t even need speakers.
02 · MEASURE
Play a sweep or noise
RTmeter stimulates the room, captures the signal, and analyzes it in real time – the reverberation time is displayed in octave bands ranging from 125 Hz to 8 kHz.
03 · SHARE
Export & Continue Planning
Save results, send them via email, or transfer them directly to the Sarooma Desktop App with a single tap to plan your actions there.
<60 sec
Fast
Scan a room and capture T20/T30 data in under a minute – right on the construction site.
Class 2
Reliable
Results of the same quality as commercial reference systems – as verified in a comparative test conducted by the Stuttgart University of Applied Sciences (02/2025).
From 80€
Affordable
Works with any external microphone and a standard Bluetooth speaker. The entire measurement system fits in a backpack.
<60 sec
Seamless
Measurement values and created rooms are exported directly as a project into the Sarooma DesktopApp.
MEASUREMENT PROCEDURES
Three Ways to Determine the Reverberation Time
RTmeter supports both the direct and indirect methods – you choose whichever is best suited to the situation on site.
Muted Noise
Broadband noise is played and then turned off – the app determines the reverberation time based on the decay of the sound pressure level.
DIRECT METHOD
Exponential Sweep
Using the sweep signal, RTmeter calculates the room impulse response through convolution and from that, precisely determines the reverberation time.
INDIRECT METHOD
Pulsed sound source
Balloon, launch flap, or origami Impulse Source: The impulse response is measured directly without any speakers at all.
WITHOUT SPEAKERS
SCIENTIFICALLY PROVEN
Validated – not just promised
In collaboration with the Stuttgart University of Applied Sciences, RTmeter was comprehensively validated as part of a bachelor’s thesis against a commercial measurement system from a well-known manufacturer.
- Several rooms with average reverberation times ranging from 0.62 s to 4.85 s
- Various hardware combinations of microphones and speakers
- Results of equivalent quality to those of Class 2 reference systems
CONFERENCE PAPER · DAGA 2025
Weigand et al.: RTmeter – Validierung einer Smartphone-App zur Nachhallzeitmessung
FREQUENTLY ASKED QUESTIONS
Good to Know
Who is RTmeter for?
For anyone who wants to measure accurate reverberation times using their smart device to identify acoustic problems, as a starting point for acoustic remediation, or to monitor project progress.
What hardware do I need?
An external, omnidirectional (measurement) microphone and except in the case of impulse response – a speaker with sufficient bandwidth, ideally connected via Bluetooth. We will publish specific model recommendations and the most important technical criteria shortly.
How exactly does the measurement work?
RTmeter plays the excitation signal through the connected speaker (or you can use a pulsed sound source), records the sound signal via the microphone, and analyzes it. Based on this, the app calculates the reverberation times in octave bands ranging from 125 Hz to 8 kHz.
Is the whole thing reliable?
Yes. RTmeter was validated in collaboration with HFT Stuttgart in several rooms with average reverberation times ranging from 0.62 s to 4.85 s and against a commercial reference system. An excerpt from the validation was presented at DAGA 2025.
SAROOMA ECOSYSTEM
From Measurement to Planning
DesktopApp
For professional planners: Room acoustics design with access to a cross-manufacturer product database – your RTmeter measurement is automatically added to the project.
→ Go to DesktopApp
WebApp & MobileApp
For product manufacturers: Calculate room acoustics projects directly using your own product line and win over customers.
→ Go to WebApp
RTmeter will be available soon
Sign up for the newsletter to be the first to hear about the launch, or contact us if you’d like to test RTmeter in your project ahead of time.