Beautiful idea, Max. If only it worked in Android! ;)

I use Smart AudioBook Player, and it does a lot of things well, but tops out at 2.5x.

If I were designing my own app, I’d have it crunch the pauses between words to get an extra boost. I’ve heard that’s how they compress the “fine print talk” on radio commercials. There are other techniques I can think of to squeeze the top performance from spoken audio recordings.