⏩ Audio Speed Changer
Play back a lecture at 1.5× permanently, or slow a riff to 0.75× to learn it — rendered on your device and saved as WAV.
Decoded, processed and encoded in your browser — recordings never touch a server.
How the audio speed changer works
The audio is decoded to samples and re-rendered at your chosen playback rate through an offline audio graph, then encoded as WAV. This is resampling: 2× halves the duration and raises pitch one octave, 0.5× doubles duration and drops it one octave — like a record played at the wrong speed. Pitch-preserving time-stretch is a different, artifact-prone algorithm; honest resampling keeps the audio clean.
Practical settings: 1.25–1.75× for lectures and podcasts (voices get chipmunk-ish beyond that since pitch shifts too), 0.5–0.75× for transcribing fast speech or learning music by ear. For casual listening most players already offer pitch-corrected speed — this tool is for when you need the changed file itself.
Frequently asked questions
Does changing speed change pitch?
Yes — this tool resamples, so speed and pitch move together (2× is one octave up), exactly like tape or vinyl at the wrong speed. That's the artifact-free method; pitch-preserving stretch smears transients and is best left to dedicated audio software.
What speed range is available?
0.5× (half speed, one octave down) to 3×. For listenable speech, 1.25–1.75× is the useful zone; beyond 2× the pitch shift makes voices hard on the ears.
How does 1.5× affect the file duration?
Duration divides by the rate: a 60-minute recording at 1.5× becomes 40 minutes; at 0.75× it becomes 80 minutes. The tool shows the output duration before you render.
Why does the output come out as WAV?
Browsers decode compressed formats but don't reliably encode them, so results are saved as universal lossless WAV. Convert to MP3 afterwards if size matters — the quality cost is the same as encoding directly would have been.
Is the audio processed on a server?
No — the offline audio renderer runs on your device. Nothing about the file, including its existence, leaves your browser.