A full version app for Android, by M-Apps.

Music Speed Changer changes audio tempo (speed) and pitches in real-time, just like a musical instrument. The app lets you create, play, and share music loops in a very easy and intuitive way.

The app has a built-in sound synthesizer, and you can use it to create your own music. It’s very easy to do: just select an audio file and mark the region you want to play. Then you can play the selected region at the desired tempo and pitch.

This is useful for practicing guitar, for instance, when making music.