Audio Tempo Changer Online
Speed up or slow down any audio while keeping pitch exactly the same. No chipmunk effect, no tape-stop — just cleaner playback at any tempo.
Change Tempo in 3 Steps
Drop your file, pick a tempo, download.
Upload Your Audio
Drag and drop an MP3, WAV, or other audio file. Up to 200 MB.
Pick a Tempo
0.5× to 2×. Pitch stays the same at every tempo.
Change & Download
Hit Change Tempo & Download. Duration changes, voices stay natural.
Why Notevibes Tempo Changer
Pitch-preserving time-stretch, no chipmunk effect.
5 Tempo Presets
0.5×, 0.75×, 1.25×, 1.5×, 2×. Half-speed for learning, double-speed for catching up.
Pitch Preserved
Voices and instruments stay at their natural pitch — no chipmunk, no tape-stop.
Privacy First
Audio is processed locally in your browser. Nothing is uploaded.
Any Audio Format
MP3, WAV, M4A, FLAC, OGG, AAC up to 200 MB.
Clean MP3 Output
192 kbps MP3 saved straight to your device — no watermark, no ads.
Works on Mobile
Change tempo on any phone or tablet. iOS, Android, all major browsers.
Your Audio Stays on Your Device
Every file is processed locally in your browser. Nothing is uploaded.
No Upload
File never leaves your device
No Account
Start changing tempo immediately
No Tracking
We never see your audio
When to Change Tempo
Most files process in seconds.
Speed up audiobooks
Listen at 1.25× or 1.5× without the voice sounding sped-up
Speed up podcasts
Cut listening time without losing speech clarity
Slow down music to learn
Drop a song to 0.75× or 0.5× to learn riffs by ear
Lecture playback
Speed up dense lectures, slow down complex passages
Match audio to video cut
Stretch a voiceover to fill the available time
Pacing rehearsal
Practice along to a song at a slower tempo, then speed up
Need Tempo + Pitch Together?
The Notevibes Audio Editor combines tempo change with pitch shift, voice changer, EQ, and effects — process whole tracks with stacked operations.
Open Full Audio EditorFrequently Asked Questions
What is a tempo changer?
A tempo changer (also called a time-stretcher) speeds up or slows down audio without changing its pitch. The audio takes more or less time to play, but voices and instruments stay at their original key — no chipmunk or tape-stop effect.
How is this different from a speed changer?
A regular speed changer plays audio faster or slower by resampling, which couples pitch and duration — fast = high-pitched chipmunk, slow = low-pitched tape-stop. A tempo changer changes only duration. To shift pitch without changing duration, use the pitch changer.
How does it work?
It uses the SoundTouchJS library, a JavaScript port of the SoundTouch phase-vocoder. The audio is broken into overlapping windows and time-stretched, so the timeline gets longer or shorter while the original pitch is maintained.
Will the audio sound natural?
Tempos near 1× sound very natural. 0.75× and 1.25× are essentially transparent. 0.5× and 2× start to introduce phase-vocoder artifacts on transients (drums, plosives) but speech remains clearly intelligible.
When should I use a tempo changer?
Speed up podcasts and audiobooks for faster listening, slow down music to learn parts, time-stretch a voiceover to match a video cut, or pace dialogue without re-recording.
Is the tempo changer free?
Yes. Completely free with no sign-up, no watermark, and no limits. Max file size is 200 MB.
Is my audio file uploaded to a server?
No. The tempo changer runs entirely in your browser. Your file never leaves your device.
What audio formats are supported?
MP3, WAV, M4A, FLAC, OGG, and AAC. Anything your browser can decode will load. Output is exported as a 192 kbps MP3.
Can I create audiobooks with Notevibes?
Yes. The AI audiobook generator turns your EPUB, Kindle, or PDF into a narrated audiobook with character detection, 550+ voices, and ACX-compliant volume normalization built in.