When a short sound is made in a room, your microphone first hears the direct sound straight from the speaker, then — a few milliseconds later — copies of it that have bounced off walls, the ceiling, the floor and furniture. Those delayed copies are early reflections; strong, distinct ones are heard as echo (a very short, tight echo off a nearby parallel wall is sometimes called a slap echo), and a rapid train of them between parallel surfaces is flutter echo. The total accumulation of all these overlapping reflections decaying over time is what acousticians call reverberation. This acoustic test tool plays a sharp click, analyzes the captured response, and measures the reflections that arrive after the direct sound — giving you a practical room acoustics diagnostic without specialized hardware.
For each click it captures a short impulse response (IR) — the amplitude envelope over the few hundred milliseconds following the click. It finds the direct peak, then looks for later peaks that stand clearly above the decaying noise floor. The first-echo delay is how long after the direct sound the strongest reflection arrives; since sound travels about 343 m/s at room temperature, that delay implies an extra path length (approximately 34 cm per millisecond). Averaging several clicks gives a stable reading and a rough liveness rating. For a complementary calculation-based estimate of reverberation time, try the RT60 reverb calculator based on your room dimensions and materials.
Reading the result
- First-echo delay — time from the direct click to the strongest reflection. Bigger rooms give longer delays.
- Implied path — the extra distance that reflection travelled (delay × speed of sound). It hints at how far the reflecting surface is, though it’s the total bounce path, not a straight-line measurement.
- Echo level — how loud the reflection is relative to the direct click (in dB). Closer to 0 dB = a very reflective surface.
- Liveness — an overall dead / balanced / live rating from the strength and persistence of reflections.
Getting a meaningful reading
- Use speakers and keep the room quiet during each click; the tool calibrates to your background noise first. Loud HVAC noise or traffic can mask quiet reflections and cause "no echo detected" results.
- Put the mic away from the speaker (and not right against a wall) so the direct sound and reflections don’t overlap.
- This is a relative acoustic indicator. A proper reverberation measurement (RT60) needs calibrated gear and a loudspeaker with known directivity. For an estimate based on room dimensions, use the RT60 reverb calculator; to check overall background noise before testing, use the background noise detector.
- Temperature and humidity affect the speed of sound slightly. At 20 °C the speed is approximately 343 m/s; warmer rooms (30 °C) raise it to about 349 m/s, introducing a small error in the implied path calculation — negligible for typical diagnostic use.
What’s the difference between echo and reverb?
They’re the same physics at different timescales. A distinct reflection arriving more than ~50 ms after the direct sound is heard as a separate echo; many overlapping reflections that blur into a smooth decay are reverb. This tool flags the discrete reflections it can resolve and rates overall liveness — it doesn’t compute a full reverb-decay (RT60) figure.
Why do I need speakers, not headphones?
The test is acoustic: the click has to travel out into the room, bounce off surfaces, and return to the microphone. Headphones put the sound straight in your ears, so there’s nothing for the room to reflect and nothing for the mic to capture. Use speakers in the room you want to test.
Why place the mic away from the speaker?
If the mic is right next to the speaker, the direct click is so dominant that early reflections hide underneath it. A bit of separation (and keeping both away from a single nearby wall) lets the direct sound and its reflections arrive at clearly different times, which is what the tool measures.
How accurate is the "implied path" distance?
It’s an estimate. The delay times the speed of sound (~343 m/s) gives the extra distance the reflected sound travelled compared to the direct path — the full bounce route, not a straight line to one wall. It’s useful for comparing rooms or surfaces, not for precise measurement.
It says "no echo detected" — what’s wrong?
Either your room is genuinely very dead (lots of soft furnishings absorb the reflections), the click volume is too low, the mic is too close to the speaker, or you’re on headphones. Raise the volume, move the mic out into the room, use speakers, and keep quiet during the test.
What is flutter echo?
A rapid, repeating series of reflections that bounces back and forth between two parallel hard surfaces (like facing walls), heard as a "boing" or buzzy ring after a clap. If the impulse response shows several evenly-spaced spikes, you likely have flutter — treat one of the parallel surfaces with absorption or diffusion.
Why does it disable echo cancellation?
Browser echo cancellation is designed to remove exactly the speaker-to-mic sound this test relies on. The tool requests the raw signal with echo cancellation, noise suppression and auto-gain off. If your system forces processing that can’t be disabled, the reflections may be partially removed and the result will under-report your room’s liveness.
Is any audio recorded?
No. The captured response is analyzed in real time to find reflections only; nothing is recorded, saved, or transmitted. The microphone is released when the test finishes or you press Stop.
Can I use this tool to check a home recording studio for acoustic treatment problems?
Yes, within limits. A "Live" liveness rating and a short first-echo delay (under 10 ms) suggest strong early reflections — common causes are bare drywall, glass windows, or hard floors. The impulse-response plot shows where those reflections come from in time; multiple evenly-spaced spikes point to flutter echo between parallel walls. For home studio acoustics, the goal is typically a "Balanced" or lightly "Dead" reading with no clear flutter pattern. This tool helps you confirm whether absorption or diffusion treatment has changed the room's behavior, though it is not a substitute for full-spectrum RT60 measurement.
What does "first-echo delay" tell me about my room size?
Because sound travels at roughly 343 m/s, a first-echo delay of 10 ms means the reflected path was about 3.4 m longer than the direct path — consistent with a reflection off a wall about 1.5–2 m away from the speaker-mic axis in a typical room. Longer delays (30–60 ms) suggest larger rooms or reflections from distant surfaces like a back wall or vaulted ceiling. Remember, this is the total bounce distance, so a 2 m room can produce the same delay as a glancing reflection off a ceiling in a larger space.
How is this different from measuring RT60 reverberation time?
RT60 measures how long it takes the overall reverberant energy in a room to decay by 60 dB after a sound stops — a single number that describes the room's total decay. This tool instead looks for discrete early reflections in the first few hundred milliseconds of the impulse response and rates their strength relative to the direct click. RT60 requires a calibrated measurement signal (e.g. a pink-noise burst or starter pistol) and averaging across multiple positions; this tool uses a simple click and is best suited for quickly diagnosing whether a room has strong reflections or flutter, not for precise acoustic design calculations.