Pitch changer

Change the pitch of audio in three steps

1. Choose an audio file or a video. A video gives you its soundtrack as an MP3.
2. Move the semitone slider between minus 12 and plus 12, and use the cents slider for small corrections.
3. Press Change pitch, listen to the preview, and download the MP3.

How the pitch shift works

Raising pitch the simple way means playing the sound faster, which also makes it shorter. This tool separates the two in two stages. First it stretches the recording in time with a method called waveform-similarity overlap-add: it cuts the sound into short overlapping pieces, and before placing each piece it searches for the position where its waveform lines up best with the previous one, so the joins stay smooth. Then it resamples the stretched audio back to the original length. Resampling moves every frequency by the same ratio, so the key changes while the duration stays put. One semitone up multiplies every frequency by about 1.06, and twelve semitones doubles it.

Changing the key of a song

Singers transpose songs to fit their range. If the chorus sits too high, try two or three semitones down; if a backing track sits too low, move it up. Each semitone is one piano key, so a song in G moved down two semitones ends up in F. If you do not know which key a song is in, the key finder on AudioClover can tell you before you transpose it. Musicians also use a pitch shifter to match a recording to an instrument they cannot retune, such as a piano, or to practice a part in a friendlier key.

Fine-tuning with cents

Some recordings are slightly out of tune with everything else: an old tape that ran fast, a vinyl rip from a turntable with speed drift, or a band that tuned to itself instead of to A 440. Those errors are usually smaller than a semitone. The cents slider moves the pitch by up to 50 cents in either direction, which is half a semitone, so you can nudge a track until it matches a tuner or a second recording. Play along on a tuned instrument and adjust in steps of five or ten cents until the slow beating between the two sounds disappears.

Limits worth knowing

A voice carries resonances, called formants, that tell your ear how large the singer is. This tool moves the formants along with the notes, so beyond about five semitones a raised voice starts to sound like a chipmunk and a lowered one like a giant. Drums and other sharp attacks can smear slightly, because the time-stretch blends overlapping pieces. The tool does not detect the key or correct single wrong notes; it moves the whole file by the same amount. The result is an MP3 at 192 kbps, which is a second lossy encoding, so keep your original. Everything runs in your browser, and nothing is uploaded.