The Audipo app is a free Android app for adjusting the speed of a song. You can use this app with audio files as follows: mp3, wav, 3gp and other low quality formats. With these you can change the speed of the song, cut it, add markers to change speed and cut in sections, split the audio and save (in the pro version only). The really great thing about this app is that it has a 4 line timeline, making it really precise in selection. The app can play in the background and while the music in pinned in the notification panel, you can still fast forward and add or remove markers. The speed can be changed from 1/4 from the original, up to 4x. There are a lot of preferences including: load markers, enable media bip, set text size, delete all mark data, color of theme, merge songs of the same album, set output folder, change size of buttons and more, vibrate on click, show hints and resume on bluetooth connected device. The Audipo is a really multi-purpose app for changing the music that you want to speed up or cut.