A free app for Android, by BandLab Technologies.

AudioStretch lets you change the pitch, speed, and volume of your audio files. Whether you’re learning to play a song, or you’re a seasoned musician, AudioStretch can help you improve your skills by making it easier to listen to your own music.

How does AudioStretch work?

First, download AudioStretch from the App Store (iOS) or Google Play Store (Android). Once you have it installed, open the app and select your audio file. You can either select it from your device’s music library, or you can use the built-in microphone to record a new audio file. 

After that, select the speed you want to play the audio file at, and you’re ready to play it. If you want to change the pitch, select the note you want to play and change the pitch by the number of semitones you want.