OneTaskBy Tim King · Updated
Pitch Shifter Online
Transpose a Song Up or Down Without Changing Tempo, With Formant Preservation
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How the Pitch Shifter works
This pitch shifter online needs no plugin or upload. Move a backing track into a comfortable key, tune a sample to a song, or nudge a recording that is slightly flat — all without changing its speed or length. Set whole semitones and a fine offset in cents, preview, and export. Everything runs in your browser and the file is never uploaded.
How the pitch shifter online works
Changing pitch on tape also changes speed, which is what the pitch-and-speed tool on this site does. Keeping the tempo fixed while the pitch moves needs a different approach: the audio is first time-stretched by the inverse of the pitch ratio, then resampled back to the original length. The two steps cancel in duration and combine in pitch. The time-stretch uses WSOLA, an overlap-add method that finds the best-matching join point for each grain so that the seams do not phase or flutter.
Semitones and cents. Twelve semitones is an octave and a hundred cents is a semitone. Use whole semitones to change key — down two to move a song from E to D — and cents for tuning corrections: a recording that is fifteen cents flat against concert pitch wants +15. The stats panel shows the combined shift and the exact frequency ratio.
Range. Up to an octave in either direction. Small shifts of one to three semitones are nearly transparent on most material. Around five or six the grain structure becomes audible on sustained tones, and at twelve the result is clearly processed. That is true of every pitch shifter, including the ones in expensive plug-ins; the quality difference is in how gracefully the artefacts appear.
Formant preservation. A voice's character comes from the resonances of the throat and mouth — the formants — which do not move when a singer changes note. A plain pitch shift moves them along with the pitch, producing the chipmunk effect upward and a giant downward. The Preserve formants option applies a spectral tilt in the opposite direction to the shift so the voice keeps more of its original timbre. It is an approximation rather than true formant tracking, and works well for shifts up to about five semitones on speech and solo vocals; on a full mix leave it off.
Tempo and length. The output has exactly the same number of samples as the input, so it lines up with the original in a video editor or against a click track.
Quality tips. Shift the highest-quality source you have. Shifting an MP3 emphasises its encoding artefacts. Export as WAV if you plan to process further.
FAQ
What is the difference from the pitch and speed tool?
That tool changes both together, like a turntable: up an octave plays twice as fast. This page changes pitch alone and the duration is untouched. Use that one for tape effects and this one for transposition and tuning.
Why does a large shift sound grainy or watery?
Time-stretching works by cutting the sound into small overlapping grains and re-joining them. The larger the shift the more the grains must be rearranged, and on sustained notes the joins become audible. Keep shifts within a fifth where possible, or shift twice in smaller steps.
Can I change the key of a whole song?
Yes. Work out how many semitones separate the current key from the target and enter that. Within three or four semitones the result is good enough for practice or a karaoke track; larger transpositions are usable but audibly processed, especially on drums.
What does Preserve formants actually do?
It tilts the spectrum opposite to the shift so that the resonances that give a voice its identity stay closer to where they were. Upward shifts get their high end cut back and downward shifts get it lifted. It reduces the chipmunk effect but does not eliminate it.
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