Engineering
Bleep and redact audio without uploading it anywhere
An AI model runs in your browser, transcribes your audio, and bleeps the words you pick. Your recording stays on your device the entire time.
7 min readRead more →
effect
Change Audio Speed Online
Speed up or slow down audio with natural pitch shift. Free, private, runs in your browser.
How it works
01
Drop your audio file or click to upload. MP3, WAV, and most formats work.
02
Use the slider or presets to set your speed (0.25x to 4x). Pitch shifts naturally with speed.
03
Preview the result and download as WAV.
No file uploadNo signupNo ads100% browser-based
Frequently asked questions
How do I change the speed of an audio file online?
Upload your audio file, use the slider to set your desired speed (0.25x to 4x), and download the result. Slower speeds lower the pitch, faster speeds raise it, just like a turntable.
Can I slow down music to learn a part?
Yes. Musicians commonly slow songs to 0.5x or 0.75x to learn difficult passages. Upload the song, set the speed, and practice along with the slowed version.
How much does the pitch change?
The tool shows the pitch shift in semitones. Doubling the speed (2x) raises pitch by 12 semitones (one octave). Halving it (0.5x) lowers pitch by 12 semitones. Each semitone is one piano key.
Can I speed up a podcast or lecture?
Yes. 1.25x or 1.5x are popular for listening to podcasts and lectures faster. Upload the audio, set the speed, and download.
Does this upload my file to a server?
No. Speed change is applied through the Web Audio API's AudioBufferSourceNode playbackRate parameter and rendered locally. Your file never leaves your device.
Can I use this on my phone?
Yes. Works in any modern mobile browser. No app needed.
What format is the output?
Lossless WAV at the original sample rate. WAV preserves full quality.
What speed works best for transcription?
0.75x is a common choice for transcription. It slows speech enough to catch every word without making it sound unnatural. For dense technical content or heavy accents, try 0.5x.
How do I slow down a song to learn it on guitar or piano?
Upload the song and set the speed to 0.5x or 0.75x. The pitch drops along with the speed, which keeps the notes in a comfortable range. Play the slowed version on repeat while you practice the passage. Once you have it, bump the speed up in small steps until you can play along at full tempo.
Can I speed up a recorded lecture or audiobook to save time?
Yes. Upload the recording and set the speed to 1.25x or 1.5x. Most speech is easy to follow at 1.5x. For dense material, 1.25x is a good starting point. Download the result and listen on any device.
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