Reverb Time Analyzer (RT60)

Drag & Drop or Click to Select a Recorded Impulse

A clap, a balloon pop, a starter pistol, or an impulse response WAV

Tip: paste an audio file from clipboard (Ctrl/⌘+V).

Mid-frequency reverberation timeISO 3382

—s

Decay curvedB / s

Shareable link

Settings are written to the URL as you change them. Nothing differs from the defaults yet.

Oxyd To put the result on a track with other audio, Oxyd is a multitrack editor with the same effects. Open Oxyd

How long a room rings. Record a clap and its decay, or load an impulse response, and the file’s squared envelope is integrated backwards from its end, the method Schroeder published in 1965, which turns one noisy decay into the smooth curve that averaging a thousand claps would give. A line is fitted to the part of that curve the standard asks for and extended to a 60 dB fall.

The curve

The plot is the broadband decay in dB against time. The shaded span is the fit window of the chosen measure and the dashed line is that fit carried to -60 dB; where the curve bends away from the line, the decay has reached the floor. The noise floor is estimated from the last tenth of the recording and subtracted before integrating, and the integration stops where the envelope meets it, so a long silent tail does not drag the slope.

Per band

Eight octave bands from 63 Hz to 8 kHz, each through its own band-pass before the same integration. Rooms decay faster at the top, where air and furnishings absorb, and slower at the bottom, where the modes are, so the table usually reads longest at 125 Hz and shortest at 8 kHz. The r beside each figure is the correlation of the fit; under 0.98 the curve was not a straight line in the window.

T20, T30 and EDT

Switch between them above the plot. T30 is the standard’s preferred figure and needs 45 dB of clean decay; T20 needs 35 and is what a clap in a quiet room usually supports. EDT is fitted over the first 10 dB, where the early reflections live, and it is the figure that tracks how live a room sounds in use.

From recording to number

The clap has to be the loudest thing in the file, since the direct sound is found as the peak. Keep the microphone away from the source so the direct sound does not clip, and keep the room quiet until the decay is below hearing. A recording that stops before the decay finishes reads short.

Feeding other tools

The dereverb step asks for the room’s RT60 to size its tail estimate; this measures it. The impulse response capture hands its measurement straight here for the per-band figures.

Frequently Asked Questions

What is RT60?

The time a sound takes to fall by 60 dB after it stops. It is rarely measured over the full 60 dB, since that needs a decay 60 dB above the noise, so the standard fits a line to part of the decay and extrapolates: T20 fits from -5 to -25 dB, T30 from -5 to -35, and EDT fits the first 10 dB, which is closest to what the ear hears as liveness.

What should I record?

One sharp loud sound and the silence after it until it has died away: a clap, a balloon pop, a starter pistol or a book dropped flat. The loudest moment is taken as the direct sound and everything after it as the decay. An impulse response from the capture tool works best, since it has energy in every band.

Why are the low bands marked unreliable?

A hand clap carries little energy under 125 Hz, so in those bands the decay sits close to the room's own noise and the fitted slope leans on that noise. The dB figure beside each band is how far its start sits above the floor: T20 needs 35, T30 needs 45. A sine sweep fixes it.

Which number do I quote?

The mid-frequency T20 or T30, the mean of the 500 Hz and 1 kHz bands, is what ISO 3382 reports as a room's reverberation time. T30 when the recording is clean enough, T20 otherwise. EDT is the one that matches how the room feels.

Explore Our Tools

Browse all tools

Impulse Response Capture

Measure a room's impulse response with a sine sweep: a sweep plays through the speakers, the microphone records the answer, the recording is deconvolved to the room's response and saved as a WAV, with its decay, frequency response and mid-frequency reverberation time read on the spot.

Audio Reverb Remover

Reduce room reverb on a recording by subtracting its own decaying tail. Set the room decay time, how much of the tail comes off, and a limit on the attenuation.

Convolution Reverb

Put a recording in a real space using its impulse response: attach a recording of the room, or pick one of four synthesized rooms, then set pre-delay and mix.

Audio Room Tone

Fill the silent gaps in a recording with its own room sound, learned from a quiet moment, so a cut never drops to nothing. Set the level under which a gap is filled, between -90 and -30 dBFS, and how fast the room fades in.

Decibel Meter

Measure sound level from the microphone with A, C, or Z weighting, Fast, Slow, or Impulse response, a running Leq, Lmax, Lmin, L10 and L90, and a calibration offset that turns the digital reading into a sound pressure level.

Audio Quality Analyzer

Read an audio file's spectral cutoff, clipped sample runs, DC offset, noise floor, and true peak in one pass, and compare the cutoff against the frequency each encoder usually stops at.

Formant Analyzer

Track the formants of a speech recording by linear prediction, Praat's method: F1 to F5 with their bandwidths every 10 ms, pitch and voicing on each frame, a vowel chart of F1 against F2 with reference vowels, and a CSV or JSON table for the notebook.

Audio Spectrum Analyzer

Plot the average magnitude spectrum of an audio file with peak hold, on a log or linear frequency axis. Set the FFT size from 1024 to 16384 samples and read the level of any band in dBFS.

Stereo Field Analyzer

Read an audio file's phase correlation, mid and side levels, left-right balance, and per-band correlation, with a goniometer scatter and the level a mono sum would cost.

Voice Quality Report (Jitter, Shimmer, HNR)

Measure a sustained vowel the way Praat's voice report does: jitter local, RAP and PPQ5, shimmer local, APQ3, APQ5 and APQ11, the harmonics-to-noise ratio, pitch statistics and the fraction of unvoiced frames, as a table, JSON or CSV.

BPM Detector

Find the tempo of a song and its beat grid: every beat and bar line drawn on the waveform, the time signature and the one, a tempo curve that shows drift, and the grid exported as markers for Oxyd or Audacity, a click track aligned to the song, or a MIDI tempo map for a DAW.

Spectrogram

Plot how an audio file's spectrum changes over time, with an FFT size from 512 to 8192, a log or linear frequency axis, an adjustable floor, and a PNG export.