Change the speed of audio

Speed up or slow down a song, a lecture or any recording in your browser without changing its pitch, from half to double speed. Free, with no upload.

AudioRinse · speed changerOn-device · 0 B uploaded

Drop audio here

MP3 · WAV · M4A · MP4 · MOV · WEBM — up to 20 min. Nothing is uploaded.

How it works

  1. Drop a song or a recording onto the box above: MP3, WAV, M4A, FLAC, or a video's sound.
  2. Press play and set the speed, from half to double. For a song, you can also type the BPM you want.
  3. The pitch stays where it was. Switch between Original and Changed to compare.
  4. Download it as MP3, M4A or WAV, as long as the new speed makes it.

Faster or slower, at the same pitch

Speeding up a tape or a record raises the pitch with it. This changes only the timing: a song slowed to 75% plays a quarter slower in the same key, and a lecture at 1.5× takes two-thirds of the time without the voice going high. The page shows the new length and, for a song, the new BPM.

How it changes pitch and speed separately

Played faster, a record also plays higher; slowed down, it plays lower. AudioRinse keeps the two apart with Signalsmith Stretch, an open-source pitch and time-stretching library made for music with many instruments at once. It cuts the sound into short overlapping slices, moves each slice's frequencies or its timing, and joins them back up, here in your browser.

You hear every change as the song plays, and the download is made the same way, faster than real time. On test tones every pitch we checked, from an octave down to an octave up, landed within 2 cents of the target, and every speed gave exactly the expected length.

What people change the speed for

  • Learning a part by ear: slow a song to 70–80% and play along, then bring it back up as you get it.
  • Dance and fitness practice at an easier tempo, or a run at a faster one.
  • Lectures, talks and voice notes at 1.25–1.5×, to get through them faster.
  • DJs matching one track's BPM to another's: type the target BPM, and the BPM finder can tell you the other track's.

Getting a clean result

  • Speech stays clear well past 1.5×; music sounds most natural between about 0.75× and 1.25×.
  • Very slow settings smear sharp sounds a little (drum hits, plucked strings); that's the nature of stretching sound in time.
  • To change the key as well, set the pitch under the speed: the two are independent.

Questions

Is my song uploaded anywhere?

No. The pitch and speed are changed inside your browser, on your own computer. Your song never leaves your device, and nothing is stored on a server.

Does it change the pitch?

No. The speed and the pitch are changed separately, so slowing a song down keeps it in the same key. You can change the pitch too, with its own control.

How slow or fast can it go?

From half speed (0.5×) to double speed (2×), in steps of 1%.

Can I set a BPM instead of a percentage?

Yes, for music: the page finds the song's tempo, and you can type the BPM you want; it sets the speed to get there.

How long can the recording be?

Up to 20 min. On a computer with little memory the page takes less, and says so.

How long does the download take?

The change is made again for the download, faster than the song plays: a 4-minute song takes 10 to 20 seconds on a recent computer. The preview is instant, since it changes the sound as it plays.

Is it free?

Changing and listening are free and unlimited. You get 3 free downloads a month for songs up to 10 minutes (1 without an account). Pro ($7.99 a month or $39.99 a year) adds unlimited downloads and songs up to 20 min, and covers every AudioRinse tool.

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