Audio pitch changer
Choose an audio file and set a shift between -12 and +12 semitones. The audio is resampled and then stretched back to its original length, so the key changes but the tempo stays the same. The result is a WAV file.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose an audio file (up to 5 minutes).
- Set the Pitch shift with the slider or number box, from -12 to +12 semitones.
- Press Change pitch. Long files take a few seconds.
- Listen to the result and download the WAV.
How it works
The ratio is 2 to the power of semitones/12. The audio is first resampled by that ratio, which shifts the pitch and changes the length, and then time-stretched back to the original length with WSOLA, an overlap-add method that picks each piece at the offset where its waveform best matches the previous one. Stereo channels use the same offsets so the image stays stable.
Worked example
+12 semitones gives a ratio of 2: a 440 Hz tone becomes 880 Hz, and a 10 s file is still 10 s. -12 gives 0.5, one octave lower. +7 gives about 1.498, a fifth higher.
Tips
- To fit a song to a singer’s range, try 1 to 3 semitones first.
- Stay within a few semitones for full mixes; the artefacts grow with the shift.
Frequently asked questions
How is this different from the speed changer?
The audio speed changer plays the file faster or slower, so pitch and length change together. This tool changes only the pitch and keeps the length, by stretching the audio back to its original duration.
What is a semitone?
The step between neighbouring keys on a piano. 12 semitones is one octave, which doubles the frequency (ratio 2); each semitone multiplies the frequency by the twelfth root of 2, about 1.0595.
Why does the sound sometimes get a bit rough?
Keeping the length means the audio has to be stretched or squeezed, which is done by overlapping short pieces. It works best on single voices and instruments and with shifts of a few semitones.
Which formats can I use?
Any audio your browser can decode, such as MP3, WAV, M4A or OGG. The result is always a 16-bit WAV file.