Room Reverb RT60 Test

Click Play Burst & Measure and the Room Reverb RT60 Test uses your microphone to capture a short noise burst plus its decay across your room, then works out a reverberation time range and a plain-language verdict on whether your space sounds clear or echoey on calls. There's nothing to type in here — just allow microphone access, keep the room quiet, and let the burst do the rest. The read your spectrum in real time is a fast way to see a live number instead of guessing by ear.

Run a Room Reverb RT60 Test on any space and you get back a single, oddly powerful number: how many seconds it takes sound to die away in that room. That number — your reverberation time — decides whether a home studio sounds tight or muddy, whether a lecture hall lets people actually understand speech, and how much acoustic treatment you'll need before either problem goes away.

None of this requires special equipment to get started — a room's dimensions and a rough guess at its surface finishes are often enough for a first estimate. This guide walks through the Sabine and Eyring formulas behind every reverb calculator and acoustic reverb calculator on the market, gives target reverberation time bands by room type, and shows exactly how many absorption panels close the gap.

What a Room Reverb RT60 Test and Reverberation Time Calculator Measure

A room reverb rt60 test answers one physics question: how long does it take a burst of sound to drop by 60 decibels after the source stops? An RT60 calculator is really just automating the math Wallace Sabine worked out at Harvard over a century ago — feed it your room dimensions and surface materials, and it returns the reverberation time you'd expect to measure with a sound level meter and a burst of pink noise. Do this early in a project and you know your acoustic climate before construction wraps up, not after. Use the train your ear using pitch discrimination to see how your results improve with practice.

A room that's too live smears consonants together and hurts speech intelligibility; a room that's too dead feels flat for music. Getting this right is as much an architectural design question as it is pure acoustic engineering.

The RT60 Formula and the Sabine Formula Behind Every Calculator

Every reverberation time calculator, this one included, ultimately runs Sabine's formula, first published in 1900:

$$ RT60 = 0.161 \times \frac{V}{A} $$

Here V is the total room volume in cubic meters, and A is the equivalent absorption area — the sum of every surface multiplied by its absorption coefficient. Push the reverberation time down and a room feels tighter; let it climb and echoes pile onto speech and music alike.

Room Volume and the Equivalent Absorption Area

The constant 0.161 assumes metric units and a speed of sound near 20°C; some calculators use 0.163 for cooler air, though the difference rarely matters. Getting the room's exact dimensions right matters more: measure length, width, and height carefully, since an error in room dimensions feeds directly into the volume and equivalent-area math. A fully reflective surface (α = 0) contributes nothing to A, while a fully open window (α = 1) contributes its entire surface area.

When to Use the Eyring Formula Instead of a Reverberation Calculator

Sabine's formula assumes sound energy is spread evenly and absorption stays low. Once average absorption climbs past roughly 0.2 — a heavily damped voice booth, for instance — Sabine starts overestimating the true reverberation time. Carl Eyring corrected this in 1930 with a logarithmic version of the same relationship:

$$ RT60 = \frac{0.161 \times V}{-S \times \ln(1-\bar\alpha)} $$

where S is total room surface area and ᾱ is the mean absorption coefficient. As ᾱ approaches 1, this formula correctly predicts a reverberation time near zero, unlike Sabine's version.

Room Acoustics in Heavily Damped Spaces

For most living rooms, offices, and a typical classroom, sound stays diffuse enough that Sabine's simpler formula is accurate within a few percent. It's mainly in acoustically extreme spaces — vocal booths, recording studios, heavily treated control rooms — where the room stops behaving like a diffuse sound field and the Eyring formula earns its extra complexity. Classroom acoustics specifically fall under DIN 18041, the German standard most acoustics consultants reference even outside Germany.

Target Reverberation Time by Room Type and DIN 18041

Once you have a measured or calculated reverberation time, the next question is whether it suits the room's use. DIN 18041 sets target bands by room type and volume rather than one universal number.

The standard defines the target using sound pressure level: RT60 is formally the time for level to drop 60 dB after the source cuts off, tracking the same drop in sound intensity a listener actually hears. Few rooms have that much clean dynamic range above the noise floor, so engineers measure a smaller drop and extrapolate.

In practice, you don't need a lab to get a usable reading. A phone app with a calibrated microphone, a balloon pop or a clap for an impulse, and free room-impulse-response software can produce a workable RT60 estimate for under the cost of a single acoustic panel. It won't match a dedicated omnidirectional speaker and precision sound level meter, but it's accurate enough to tell you whether a room needs a little damping or a lot — usually the decision that matters most before you start buying treatment.

T60, T30, and T20 in Practice

T30 measures the drop from -5 dB to -35 dB and doubles it; T20 measures from -5 dB to -25 dB and multiplies by three. Both are workarounds engineered to converge on the same T60 value a full 60 dB reading would give, and both are reported per octave or frequency bands rather than as one flat reverb time, since a room doesn't behave identically at every pitch.

The audio signal used for the test is typically a burst of pink noise or a starter pistol, chosen because it excites all frequency bands roughly evenly. Physically, it's the same sound wave losing energy at each reflection off every surface until the level drops below what you can hear.

How Many Acoustic Panels You Need After a Sound Absorption Reading

Once you know your current reverberation time and your target, the missing sound absorption follows directly from rearranging Sabine: A = 0.161 × V / T, calculated once at your current state and once at target. The gap between the two is the extra absorbing area you need from acoustic panels.

Real acoustic panel products don't ship with a raw number — they ship with αw, the weighted absorption coefficient defined by ISO 11654 and derived by fitting a reference curve to the product's measured performance across octave bands. To estimate panel count, divide the missing absorbing area by one panel's area times its αw.

Here's a concrete example: a 4 m × 5 m room with a 2.5 m ceiling height works out to 50 cubic meters. If it currently reads 0.9 seconds and a target of 0.6 seconds applies, plugging both into the rearranged formula gives roughly 8.9 square meters of absorption today versus 13.4 square meters at target — a shortfall of about 4.5 square meters.

Divide that by a single panel's contribution (0.72 square meters of panel at αw 0.85 works out to about 0.61 square meters of absorption per unit) and you land on roughly 7 to 8 panels to close the gap. Doubling the panel count rarely doubles the improvement, though — once a room is already close to target, each additional panel buys a smaller drop in seconds, so it's worth re-checking the numbers after the first batch goes up rather than over-ordering up front.

• A tighter reverberation time target for a given room means more absorption is needed overall.
• Furnishings and a single ceiling baffle both chip away at reverberation time before you add wall panels.
• An open-plan office needs absorption spread across multiple surfaces, not concentrated on one wall.
• Swapping a hard floor for a heavier floor covering is often the cheapest way to add absorption.
• Re-run the numbers through a reverberation time calculator after adding panels to confirm the room lands inside its target band.

1. Measure the room's volume and exact dimensions.
2. List every surface with its absorption rating.
3. Multiply each surface by its rating and sum into the equivalent absorption area.
4. Apply the RT60 formula — Sabine for typical rooms, Eyring for heavily damped ones.
5. Compare the result against your target reverberation time for that room's use.

Sound engineering, audio engineering, and interior design all touch this problem from a different angle, but architectural acoustics ties them together: the building materials chosen during construction set a room's baseline acoustic climate long before anyone hangs an acoustic panel. Good acoustics are cheaper to design in than to retrofit. Good sound design and real noise control both start with the same RT60 calculator you'd use to check a finished space, and the same handful of variables every reverberation time standard ultimately comes back to.