Audio Speed Changer

How to use the audio speed changer

1. Open the audio file.
2. Choose a speed, or use a preset.
3. Render the result and download it.

About this tool

Speed and pitch move together here, exactly as they do when a record is played at the wrong speed: at 1.25× everything is about 3.9 semitones higher, at 0.5× an octave lower. The shift is shown in semitones so the effect is predictable rather than a surprise.

Keeping the pitch while changing the speed is a different technique — time-stretching — which needs phase-vocoder processing that a simple playback-rate change cannot do. This tool does not claim to do it, because doing it badly sounds far worse than the honest version.

Slowing audio down is genuinely useful for transcription and for learning a musical part; speeding it up works well for lectures where a modest pitch rise is barely noticeable.

Browsers can decode MP3, M4A, OGG and FLAC, but the only format they can reliably write is WAV — so the output here is WAV. Exporting MP3 would mean bundling an encoder several times the size of this entire site, which is not a trade worth making for a tool you use once.

Common uses

• Slowing a recording down to transcribe it.
• Speeding up a lecture recording.
• Slowing a musical phrase to learn it.

Frequently asked questions

Can it change speed without changing pitch?

No. That requires time-stretching, which is a different technique. This changes the playback rate, so pitch moves with it.

How much does the pitch change?

Doubling the speed raises the pitch by an octave. The exact shift in semitones is shown as you move the slider.