Audio speed changer

Change the speed of audio in three steps

1. Choose an audio file, or try the included sample.
2. Set a speed between 0.5 and 2 times. Add a pitch shift in semitones if you want to change the key.
3. Press Change speed, listen to the preview, and download the new MP3.

Speed up without the chipmunk voice

Playing a recording faster the simple way raises its pitch, which is why speeded-up voices sound squeaky. This tool stretches the audio in time instead. It splits the sound into short overlapping pieces and re-assembles them closer together, so speech at 1.5 times speed keeps its natural pitch. This works best on speech and clean music, and extreme settings can add a faint warble.

Slow down to learn or transcribe

Slowing a recording to 0.75 or 0.5 times makes fast speech easier to follow. Musicians slow down a solo to pick out the notes, language learners slow a clip to hear each word, and transcribers work at a pace they can type at. The pitch stays where it was, so the slowed audio is still easy to recognise.

Change the key with pitch

The pitch control moves the recording up or down in semitones, from minus twelve to plus twelve. One semitone is the step between neighbouring piano keys, and twelve is a full octave. Use it to fit a backing track to your singing range, or to make a voice deeper or higher without changing how long it takes. Large shifts change the character of a voice.

Speed up a long recording

Listening to a lecture at 1.25 or 1.5 times saves time without losing comprehension for most people. Save the result as an MP3 and play it anywhere. For very long files the process can take a minute, because it works through the whole recording on your device.