Audio Source Moving @ Supersonic Speed

Let's say I have an indestructible speaker and I launch it out of a cannon at Mach 1.5 while it's playing music. (To make things simple, it also has an iPod and battery attached to it.) If the speaker passes a stationary observer, will they hear each cycle of the sound wave from the speaker in reverse order after the speaker passes them?

I remember reading a paper about this, but I can't find it anywhere now and I'm starting to think maybe I imagined it.