How to use it
- Open a file.
- Set the shift in semitones: +1 is one piano key up, −12 a full octave down.
- Press "Apply pitch shift" and listen. Change the value and apply again; it always starts from the original.
- Download.
Pitch without speed
Speeding a tape up raises pitch and shortens it at the same time. To change only pitch, VocalForge first time-stretches the audio with WSOLA (overlapping small windows that are lined up by similarity) and then resamples it back to the original length. Shifts within ±4 semitones sound most natural; larger shifts start to sound processed, especially on voices.
What a semitone shift does to frequency
Each key on a piano is one semitone. Moving up one key multiplies the frequency by about 1.0595, and twelve keys double it. Tap a key to hear the note and see the ratio the pitch changer would apply.
0 semitones · A · 220.0 Hz · ratio ×1.0000
Starting note A3 = 220 Hz. At +12 you reach A4 = 440 Hz, the tuning reference used by most orchestras (ISO 16).
Questions
Is my audio uploaded anywhere?
No. The file is decoded, processed and encoded by your own browser using the Web Audio API. Nothing is sent to a server, which is also why it works on large files without a queue.
How much is one semitone?
A frequency ratio of the twelfth root of two, about 1.0595. Twelve semitones double the frequency, which is one octave.
Will the song get faster or slower?
No. The pitch changer keeps the original duration. Use the Audio Speed Changer if you want to change tempo.