Audio Speed Changer
Speed up or slow down audio files online for free.
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What is Audio Speed Changer?
The Audio Speed Changer resamples or time-stretches audio files directly in your browser with the Web Audio API. Choose any speed from 0.25x to 2x, optionally preserve the original pitch with an overlap-add time-stretcher, preview the processed result in the page, and download it as a WAV file - with no upload at any point.
Key Benefits
- Fast-forward through long recordings without chipmunk voices
- Slow down fast speech until every word is clear
- Optional pitch preservation with overlap-add stretching
- In-page preview before you commit to a download
- Private by design - audio never leaves your machine
Common Use Cases
- •Speeding through lecture recordings and podcasts
- •Slowing down language-learning audio for practice
- •Adjusting demo audio to fit a video timeline
- •Turning any audio into a slower practice loop for music
How to Change Audio Speed
- Choose the audio: Select an MP3, WAV, OGG or M4A file from your device.
- Set the speed: Move the slider between 0.25x and 2x and choose whether to preserve pitch.
- Process and preview: Press Process audio, then listen to the result right on the page.
- Download the WAV: Save the processed audio as a WAV file playable anywhere.
Key Features
- Speed range from 0.25x up to 2x
- Optional pitch preservation via overlap-add time stretch
- Web Audio offline rendering for fast processing
- In-page preview of the processed audio
- WAV export playable anywhere
- No upload - audio stays on your machine
Frequently Asked Questions
What does preserve pitch do?
Without it, faster playback simply resamples the audio, so voices rise and slowed voices drop. Pitch preservation uses an overlap-add time-stretcher to change the pace while keeping voices at their original pitch.
Which file types can I load?
Anything your browser can decode - MP3, WAV, OGG and M4A in practice. The processed result is always exported as a 16-bit WAV file.
Why does the output sound slightly rougher with pitch preservation?
Time-stretching re-assembles the audio from overlapping grains, which can add subtle artifacts on complex material. Try turning preservation off if the original pitch change is acceptable.
Is my audio uploaded anywhere?
No. Decoding, stretching and WAV encoding all happen in your browser with the Web Audio API - the file never leaves your machine.