Does speeding audio up change the pitch?

It depends which of the two modes you are in, and that is the whole reason this page has both. Speed asks the browser to hold the pitch while it stretches the time, which is what you want for a lecture, a podcast or an audiobook: 1.5x is shorter, the voice is still the voice. Speed + pitch does what a tape machine or a record player does, coupling the two, so 2x is one octave up and 0.5x is one octave down. The page shows the shift in semitones, worked out as 12 times the base-two logarithm of the rate, so 1.25x reads +3.86 semitones. If your browser does not provide a time stretch, the Pitch cell says so rather than pretending: in that browser the pitch moves with the rate, and the page tells you before you press Play.

Can I download the file at the new speed?

Rate-coupled speed, reverse and gain download as uncompressed 16-bit PCM WAV. Pitch-preserved speed is playback only: this tool cannot render the browser’s pitch-preserving playback into an exported buffer. Rate coupling does not resample the already decoded sequence; it changes the sample rate written in the WAV header. Every WAV export rounds decoded float samples to 16-bit PCM and clips samples beyond full scale. A header holds a whole number of hertz: at 1.234x, a decoded 44,100 Hz buffer is written at 54,419 Hz rather than 54,419.4 Hz. The decoder’s buffer rate may differ from the original file’s rate, and the page prints the header rate it writes.

Which files can I open, and is there a size limit?

Open a file that your browser can decode with Web Audio. If decoding fails, the tool reports it rather than claiming support for that file. The existing limits are 120 MB of source file and 30 minutes of decoded audio; files over either limit are refused with a message. Processing happens in this tab, where decoded audio occupies more memory than a compressed file.

Is reversing audio here lossless?

Reversing places the decoded samples in the opposite order without changing their values, duration or sample rate. Reversing that sample sequence twice restores it. The saved WAV is 16-bit PCM, which rounds the decoded 32-bit float samples; a previously lossy source cannot regain information discarded before decoding.

How much can I raise the volume of a quiet recording?

The gain control runs from -24 dB to +24 dB, and it is plain multiplication: amplitude equals 10 to the power of the decibels over 20, so +6 dB is roughly double the amplitude and -6 dB is roughly half. The page prints that formula next to the result. Raising a quiet track has a hard limit, which the readout makes visible: the loudest sample decides how much headroom there is, and past that point samples hit full scale. They are clamped there rather than allowed to wrap, because a wrapped sample flips sign and cracks exactly where the audio was loudest, and the readout counts how many samples would clip before you download anything. The preview applies the same gain and full-scale clipping as the export, then plays at half level. The exported WAV carries the whole gain, quantized to 16-bit PCM.

Is my audio uploaded anywhere?

Your recording is decoded and processed in this browser tab. The tool does not upload its audio, filename or samples. It remembers the mode, speed and gain in this browser; Start over clears those settings, and blocked storage leaves the default settings available.

Can I use it without a mouse?

Yes. The speed is an ordinary text field: type 1.25x, or 125%, or just 1.25, and press Enter. With that field focused the up and down arrows move the speed by 0.05 at a time, and in Speed + pitch the semitone field takes +12 or -5 and sets the speed to match. The gain field works the same way, moving a decibel per arrow press. The space bar plays and stops from anywhere outside a field or a button, the mode buttons and the speed chips are ordinary buttons in the tab order, and anything typed that is not a number is refused with the form to type instead, rather than quietly becoming 1x.

Can I use this audio speed changer on Windows, Mac, Android or iPhone?

The core tool runs in your browser without an account or software installation. Local file decoding and pitch preservation depend on that browser. Use Speed + pitch for a rate-coupled WAV export, Reverse for reversed audio, or Gain to change the whole recording’s level. It does not change system volume or export a video.

Audio Speed Changer

Open a local recording to change speed, reverse its samples or adjust gain. Speed mode asks your browser to preserve pitch for playback; Speed + pitch couples pitch to speed. Rate-coupled speed, reverse and gain can download as 16-bit PCM WAV, while pitch-preserved playback does not export.

Open an audio file

· or drop one anywhere on the stage

Never uploadedNo accountUp to 120 MBUp to 30 minutes

Mode

Speed

Pitch: Preserved

Length: 0:00.000

Export: WAV

Ready. Choose an audio file, or drop one on the stage.

1.25x, pitch kept3:20.000 example source
2:40.000, same pitch, plays only
0.5x, pitch moves3:20.000 example source
6:40.000, pitch -12 semitones
Reverse3:20.000 example source
3:20.000 backwards, same pitch

Speed takes any value between 0.25x and 4x: type it in the field as 1.25x or 125%, press the up and down arrows to move it 0.05 at a time, or press one of the chips on the stage. In Speed + pitch the semitone field sets the speed to match, so +12 semitones is 2x. Space plays and stops. The ceilings are 120 MB and 30 minutes, because the whole file is decoded to 32-bit samples in the memory of this tab. Gain runs from -24 dB to +24 dB and plays back at 50% of the level it writes, so a boost does not arrive at full volume in your headphones, and the readout counts the samples that clip before you download anything. The file is never uploaded and never sent anywhere.

What is exact, and what the browser decides. Playback speed is exact and the new length is the old one divided by the rate. Pitch preservation uses the browser's own time stretch, is not available in every browser, and cannot be written to a file: only a rate-coupled speed change, a reverse or a gain change exports as WAV. Gain multiplies every sample and clips at full scale, and the page counts the clipped samples before you export.

Common questions

Does speeding audio up change the pitch?: It depends which of the two modes you are in, and that is the whole reason this page has both. Speed asks the browser to hold the pitch while it stretches the time, which is what you want for a lecture, a podcast or an audiobook: 1.5x is shorter, the voice is still the voice. Speed + pitch does what a tape machine or a record player does, coupling the two, so 2x is one octave up and 0.5x is one octave down. The page shows the shift in semitones, worked out as 12 times the base-two logarithm of the rate, so 1.25x reads +3.86 semitones. If your browser does not provide a time stretch, the Pitch cell says so rather than pretending: in that browser the pitch moves with the rate, and the page tells you before you press Play.
Can I download the file at the new speed?: Rate-coupled speed, reverse and gain download as uncompressed 16-bit PCM WAV. Pitch-preserved speed is playback only: this tool cannot render the browser’s pitch-preserving playback into an exported buffer. Rate coupling does not resample the already decoded sequence; it changes the sample rate written in the WAV header. Every WAV export rounds decoded float samples to 16-bit PCM and clips samples beyond full scale. A header holds a whole number of hertz: at 1.234x, a decoded 44,100 Hz buffer is written at 54,419 Hz rather than 54,419.4 Hz. The decoder’s buffer rate may differ from the original file’s rate, and the page prints the header rate it writes.
Which files can I open, and is there a size limit?: Open a file that your browser can decode with Web Audio. If decoding fails, the tool reports it rather than claiming support for that file. The existing limits are 120 MB of source file and 30 minutes of decoded audio; files over either limit are refused with a message. Processing happens in this tab, where decoded audio occupies more memory than a compressed file.
Is reversing audio here lossless?: Reversing places the decoded samples in the opposite order without changing their values, duration or sample rate. Reversing that sample sequence twice restores it. The saved WAV is 16-bit PCM, which rounds the decoded 32-bit float samples; a previously lossy source cannot regain information discarded before decoding.
How much can I raise the volume of a quiet recording?: The gain control runs from -24 dB to +24 dB, and it is plain multiplication: amplitude equals 10 to the power of the decibels over 20, so +6 dB is roughly double the amplitude and -6 dB is roughly half. The page prints that formula next to the result. Raising a quiet track has a hard limit, which the readout makes visible: the loudest sample decides how much headroom there is, and past that point samples hit full scale. They are clamped there rather than allowed to wrap, because a wrapped sample flips sign and cracks exactly where the audio was loudest, and the readout counts how many samples would clip before you download anything. The preview applies the same gain and full-scale clipping as the export, then plays at half level. The exported WAV carries the whole gain, quantized to 16-bit PCM.
Is my audio uploaded anywhere?: Your recording is decoded and processed in this browser tab. The tool does not upload its audio, filename or samples. It remembers the mode, speed and gain in this browser; Start over clears those settings, and blocked storage leaves the default settings available.
Can I use it without a mouse?: Yes. The speed is an ordinary text field: type 1.25x, or 125%, or just 1.25, and press Enter. With that field focused the up and down arrows move the speed by 0.05 at a time, and in Speed + pitch the semitone field takes +12 or -5 and sets the speed to match. The gain field works the same way, moving a decibel per arrow press. The space bar plays and stops from anywhere outside a field or a button, the mode buttons and the speed chips are ordinary buttons in the tab order, and anything typed that is not a number is refused with the form to type instead, rather than quietly becoming 1x.
Can I use this audio speed changer on Windows, Mac, Android or iPhone?: The core tool runs in your browser without an account or software installation. Local file decoding and pitch preservation depend on that browser. Use Speed + pitch for a rate-coupled WAV export, Reverse for reversed audio, or Gain to change the whole recording’s level. It does not change system volume or export a video.

Playback speed is exact and the new length is the old one divided by the rate. Pitch preservation uses the browser's own time stretch, is not available in every browser, and cannot be written to a file: only a rate-coupled speed change, a reverse or a gain change exports as WAV. Gain multiplies every sample and clips at full scale, and the page counts the clipped samples before you export.