How to speed up or slow down audio without changing pitch

Speeding audio up or slowing it down is useful for everything from fitting a voiceover into a time slot to slowing a song to learn a part. The catch is the "chipmunk effect" — naively changing speed also raises or lowers the pitch. The fix is a feature called pitch preservation, which changes the tempo while keeping voices and instruments sounding natural.

This guide uses the free AudioTrim editor, which runs in your browser with a pitch-preservation option built in. Nothing is uploaded, so you can re-time a private recording without it leaving your device.

Speed vs. pitch — the key idea

Imagine playing a vinyl record faster: it finishes sooner, but everyone sounds like a chipmunk because the pitch rises along with the speed. That's the simple, linked behavior. Pitch preservation decouples the two — the audio plays faster or slower, but a person's voice stays at the same pitch it always was. For speech and music you almost always want pitch preserved; for sound-effect experiments you might want the linked, pitch-shifting version instead.

Step by step

1. Open your file. Drag an audio file onto audiotrim.app.
2. Turn on Preserve pitch. Make sure the Preserve pitch option is enabled before you change the speed. This is what keeps voices natural.
3. Set the speed. Drag the Speed slider. Values above 1.00× play faster; below 1.00× play slower. The editor supports up to 3× for fast playback and well below 1× for slowdown.
4. Listen. Press Play and check that it sounds right. With Preserve pitch on, a sped-up voice should sound like the same person talking faster — not higher.
5. Compare modes (optional). Toggle Preserve pitch off and on to hear the difference. Off gives the classic faster-and-higher (or slower-and-lower) effect; on keeps the original pitch.
6. Download. Export the re-timed audio as MP3 or WAV.

How far can you push it?

Pitch preservation is excellent for moderate changes — roughly 0.5× to 2× — where the result sounds completely natural. Push to extremes and you may hear slight smearing or a "watery" artifact, because the algorithm is reconstructing audio that was never recorded at that tempo. For most real tasks (speeding up speech, slowing a riff) you'll stay well inside the clean range. If you only care about the effect and not realism, turning Preserve pitch off can sound fine at any speed.

Frequently asked questions

Why does my sped-up audio sound high-pitched?

Preserve pitch was probably off. Turn it on and reapply the speed change; the pitch will stay at the original.

Can I slow audio down to learn a song?

Yes — set the speed below 1× with Preserve pitch on. The notes stay in the same key, just slower, which is ideal for practice and transcription.

Does changing speed lose quality?

Moderate changes are essentially transparent. Extreme stretches can introduce mild artifacts. Export at a higher bitrate to keep things crisp.

Can I speed up only part of a clip?

The speed control applies to the loaded audio as a whole. To re-time just a section, trim that section out first, change its speed, then merge it back with the rest using Append file.

Change the speed now →

Related: How to trim a recording · How to merge MP3 files · All guides