Audio Speed Changer
Adjust playback speed from 0.25× to 4× — pitch stays constant. Drop a whole folder and process them all at once.
Good for burning through a lecture backlog at 1.5× or 2×.
Drop files here
or click to browse · paste from clipboard
Accepts .MP3, .M4A, .WAV, .OGG, .FLAC, .AAC · Up to 1,000 files
How it works
Drop your files
Drag and drop, click to browse, or paste from clipboard. Up to 1,000 files at once.
Choose settings
Adjust quality, format, and other options to match your needs.
Click Convert
Everything runs in your browser via WebAssembly. Audio Speed Changer happens locally — no server involved.
Download
Download files individually or grab all at once as a ZIP.
Frequently asked questions
No. The tool uses ffmpeg's atempo filter, which time-stretches the audio while keeping pitch constant. Speech stays at normal pitch at 2× speed; slowed-down music stays in the original key.
ffmpeg's atempo filter supports 0.5× to 2× per pass. To hit 0.25× or 4×, the tool chains two atempo filters in sequence. The result sounds natural within reason — extreme values like 0.25× will make audio sound artificially sluggish.
Slightly. Speed adjustment requires re-encoding, which adds a small quality cost. For voice and podcasts this is inaudible. For high-fidelity music, choose WAV output to minimize codec losses.
Yes. Drop as many files as you need — all get the same speed multiplier. Results are packaged in a ZIP.