Audio Speed Changer

Audio Speed Changer makes a recording play faster or slower, holding the pitch steady by default or letting it move with the speed if you turn that off.

With the pitch lock on, the change is made by the atempo time-stretch filter, and because a single atempo stage only covers 0.5x to 2x, anything outside that is built as a chain — 3x becomes a 2x stage followed by a 1.5x one. Switch the lock off and the file is resampled instead, which is the chipmunk effect: the audio speeds up and the pitch rises with it, the way a record played at the wrong speed does. Time-stretching is an approximation, so large settings leave a smeared, faintly metallic quality on music, and asking for exactly 1x is refused because it would re-encode the file and change nothing.

The stretch is computed by your own processor inside the page. Nothing is uploaded, and the result exists only as a download you choose to save.

Slowing a fast lecture down enough to take notes from it, speeding an audiobook up without the narrator sounding higher, dropping a music phrase to half speed to learn it by ear, and fitting a voiceover to a fixed video length.

Also known as: speed up audio · slow down song · tempo changer · change music speed without pitch · mp3 speed changer