What is Speed/Pitch Changer?

Speed/Pitch Changer lets you adjust the playback speed and pitch of any audio file independently. Slow down music to learn parts, speed up podcasts, shift pitch for vocal training, or create fun effects. Preview changes in real-time and download the modified audio.

Speed and pitch are decoupled with a phase-vocoder algorithm — moving the speed slider from 1x to 0.5x makes the audio play at half tempo while the pitch stays where it was, so a vocal does not drop an octave. The pitch slider spans ±24 semitones (two octaves) for transposing a song into your range, and a 10-band equalizer with genre presets lets you boost bass or bring out vocals. Export to lossless 16-bit WAV or to MP3 when you need a smaller file to share.

How to use

1. Upload an audio file — MP3, WAV, OGG, and other common formats are supported.
2. Adjust the speed slider (0.25× to 4×) and pitch slider (±24 semitones, two full octaves). Changes preview in real-time as you play.
3. Download the modified audio as WAV or MP3 when you're happy with the result.

When to use

• Practising an instrument by slowing a fast solo to half speed while keeping the original key.
• Speeding through long podcasts or lectures without making everyone sound like a chipmunk.
• Shifting the pitch of a karaoke track up or down to match your vocal range.

Result

You're learning a fast guitar riff. Upload the song, slow it to 0.5× speed without changing the pitch, and practice along. Once comfortable, gradually increase speed back to 1× while keeping the same pitch.

FAQ

Why does changing speed not change pitch here, when it does on YouTube?

YouTube uses time-stretching too, but only at preset speeds. This tool gives you fine control between 0.25x and 4x and uses a phase vocoder that processes overlapping windows of audio, preserving pitch independently from playback rate.

What does +12 semitones actually mean?

Twelve semitones equal one octave, so +12 doubles the perceived pitch (a male voice ends up near female range) and -12 halves it. Each step is one half-tone of a piano. Most singers prefer 1–4 semitone shifts to match a comfortable key.

Why does extreme slowdown sound a bit watery or smeared?

Phase vocoders introduce small smearing artifacts because they reconstruct audio from overlapping frequency snapshots. At 0.25x or 0.5x for long stretches the artifacts become audible. For practice that's usually acceptable; for final output, stay closer to 0.7x.

Can I change speed without preserving pitch (the old tape effect)?

Yes — disable the Preserve toggle. Audio then plays back like an analog tape: 2x speed shifts everything up one octave, 0.5x drops it down one octave. Useful for creative effects but unusable for practice.

Should I export as WAV or MP3, and will the quality hold up?

Pick WAV for the best quality — it's 16-bit PCM at the original sample rate, CD-quality and lossless, ideal for further editing. Pick MP3 (192 kbps) when you want a much smaller file to share or upload. Either way the phase-vocoder step adds only tiny artifacts at extreme settings; at moderate speed and pitch changes the result is hard to tell from the source.

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