Audio Speed and Pitch
Change audio playback speed and pitch independently or preserve natural vocal tone during tempo shifts. All processing runs entirely inside your web browser.
MP3, WAV, M4A, AAC, OGG, FLAC, Opus · up to 1 GB
Tips
- The browser downloads a 30 MB processing engine on first use and caches it for offline work.
- Enable pitch preservation to keep spoken voice frequencies natural when speeding up podcasts or lectures.
- Playback rates above 1.5x reduce speech intelligibility unless listeners are trained on accelerated audio.
How to use it
- 1 Upload your audio file into the tool.
- 2 Set your desired playback speed multiplier and pitch adjustment.
- 3 Choose whether to preserve the original tonal pitch during tempo changes.
- 4 Process and save the re-timed audio file to your local drive.
What you should know
Adjusting audio tempo without altering pitch requires time-stretching algorithms rather than simple sample rate resampling. Simple playback rate increases shift spectral frequencies upward, producing an unnatural high-pitched sound, while lowering playback speed drops the pitch into an unreadable rumble. Phase vocoder and overlap-add processing analyze phase coherence across frequency bins, allowing you to accelerate lectures, transcribe spoken interviews, or practice musical passages without modifying tonal keys. However, extreme tempo changes introduce phase smearing or transient blurring, especially on complex multi-instrumental mixes where overlapping harmonics conflict during temporal expansion or compression.
This tool runs entirely within your browser via a WebAssembly engine, eliminating server uploads and protecting private voice recordings. You can alter playback speed and pitch together or lock the pitch while changing tempo across standard formats like MP3, WAV, and AAC. The engine compiles the output through single-threaded processing, so long recordings may take several minutes to re-encode depending on your CPU. The exported file preserves your channel layout while applying your selected tempo adjustments directly to the uncompressed PCM stream before encoding to the target container.
Frequently asked questions
Does speeding up audio distort speech or make voices sound high-pitched?
If you enable pitch preservation, the tool alters playback duration without shifting tonal frequencies, keeping voices natural. Without pitch correction, increasing speed shifts all frequencies upward.
Are my audio files uploaded to an external server?
No, all audio processing occurs locally inside your browser using a WebAssembly engine. Your media files never leave your computer or mobile device.
Why does exporting a long audio file take several minutes?
The WebAssembly engine operates on a single CPU thread to decode, resample, and re-encode audio frames. Processing time scales with the length and sample rate of the input file.
Guides
Articles and format references related to this tool.
Related tools
- Audio Joiner Merge multiple audio files into a single track with custom ordering and smooth crossfades. Processing runs entirely in your browser without file uploads.
- Audio Fade In Out Apply smooth audio fade in and fade out effects by setting custom durations in seconds. Process files privately inside your browser without uploading.
- Audio Volume Adjuster Adjust audio volume by decibels or normalize peak levels to minus one dB directly in your browser. Prevent harsh digital clipping without uploading files.
- FLAC to M4A Converter Convert FLAC audio to M4A AAC right in your browser. Choose custom bitrates, reduce file size, and keep all your sound data private without server uploads.
- FLAC to OGG Converter Convert FLAC audio files to OGG format in your browser. Adjust bitrates, preview the sound instantly, and keep your audio private without server uploads.
- WAV to OGG Converter Convert raw WAV master tracks to compact OGG Vorbis audio in your browser. Adjust bitrates for pristine game assets and web playback without server uploads.