Audio Speed Changer
Upload any audio file (MP3, WAV, OGG) and adjust playback speed from 0.25x to 2.0x for music practice, transcription, or analysis. Slow down fast guitar solos to learn them note by note, or speed up practice tracks to push your tempo. Features include play/pause/stop controls, current time display, waveform visualization via Canvas, and loop markers to repeat a specific section (set A and B points). Uses the Web Audio API AudioBufferSourceNode for clean playback with adjustable speed. Note that speed changes also affect pitch proportionally — this is actually useful for musicians practicing at different tempos.
Tips for Practice
- Upload any audio file (MP3, WAV, OGG, M4A, FLAC)
- Slow down to 0.5x or 0.75x to learn difficult passages
- Use A-B loop to repeat a specific section
- Speed changes also affect pitch — useful for transposing practice
- All processing happens in your browser — no audio is uploaded to any server
How to Use
- 1
Upload an Audio File
Click the upload area or drag and drop an MP3, WAV, or OGG file. The tool loads the audio into memory using the Web Audio API so playback and speed changes happen instantly.
- 2
Adjust Playback Speed
Use the speed slider to set playback rate from 0.25x (quarter speed) to 2.0x (double speed). Note that changing speed also changes pitch — slowing down lowers the pitch, speeding up raises it.
- 3
Use Loop Points
Set A and B markers to define a section of the track to loop repeatedly. This is essential for practicing difficult passages — isolate 4 bars and loop them at 50% speed until mastered.
- 4
Control Playback
Use play, pause, and stop buttons to control the audio. A waveform visualization shows the full track with a playhead indicator so you can see your position and the loop region.
Examples by Niche
Load a track with a fast guitar solo, slow it to 0.5x speed, and set loop markers around the solo section. Play it repeatedly at half speed to pick out each note for transcription.
Speed up a song to 1.25x to practice a routine at a faster tempo, building muscle memory. Then return to 1.0x for the actual performance tempo.
Load a podcast or audiobook in a foreign language and slow it to 0.75x. Loop difficult sentences to catch pronunciation details that are too fast at normal speed.
Isolate a 2-bar drum fill using loop markers and slow it to 0.3x. Practice along with the slowed audio, gradually increasing speed from 0.3x to 0.5x to 0.75x to full speed.
Frequently Asked Questions
Does changing speed also change the pitch?
Yes — the Web Audio API playbackRate changes both speed and pitch proportionally. At 0.5x speed, the audio plays one octave lower. At 2.0x speed, it plays one octave higher. For musicians learning parts by ear, this is often acceptable and even helpful. True pitch-preserved time stretching requires specialized DSP libraries not included in the basic Web Audio API.
What audio formats are supported?
The tool supports MP3, WAV, and OGG files — any format that your browser's Web Audio API can decode. Most modern browsers support these three formats natively. File size is limited only by your browser's available memory since the audio is decoded into an in-memory buffer for playback.
How do the loop markers (A-B loop) work?
Click "Set A" to mark the loop start point and "Set B" to mark the loop end point during playback. The audio will continuously loop between these two points, which is invaluable for practicing difficult passages in a song. Clear the markers to return to normal playback. Loop points are displayed on the waveform visualization.
Can I use this to learn guitar solos and fast passages?
Absolutely — this is one of the most effective practice techniques. Set the speed to 0.5x or 0.25x to hear every note clearly, use A-B loop markers to isolate the passage, then gradually increase the speed as you master each phrase. Professional musicians and music teachers have used slow-down tools like this for decades.