Pitch changer

Every note moves by the same amount, and nothing else does: the song keeps its speed and length. A semitone is one piano key, so +2 moves a song in C up to D, and 12 semitones is a whole octave. Cents split a semitone into 100, for tuning to an instrument that isn't at concert pitch.

Once the song's key is found, the page names the key you'll end up in, with its Camelot code.

Played faster, a record also plays higher; slowed down, it plays lower. AudioRinse keeps the two apart with Signalsmith Stretch, an open-source pitch and time-stretching library made for music with many instruments at once. It cuts the sound into short overlapping slices, moves each slice's frequencies or its timing, and joins them back up, here in your browser.

You hear every change as the song plays, and the download is made the same way, faster than real time. On test tones every pitch we checked, from an octave down to an octave up, landed within 2 cents of the target, and every speed gave exactly the expected length.

• One to three semitones either way sounds natural on almost any music: it's what singers and bands do when they transpose a song.
• Voices give it away first. Four or five semitones up and a singer starts to sound young and thin; down, heavy and slow. Instruments stand larger changes.
• An octave up or down is there for practice and effects, not for a natural result.

• Singing a song in your own range: lower it a couple of semitones if the high notes strain.
• Playing along with a recording that's tuned differently, or in a key your instrument doesn't suit.
• Learning a fast solo by ear, with the speed slowed down too.
• Mixing two songs in key: the key changer picks the shift for you, and the Camelot wheel shows which keys mix.