Core Audio gets a bunch of neat new tricks in iOS 6, particularly for developers working with Audio Units. New effect units include an improved ability to vary pitch and playback speed, a digital delay unit, and OS X's powerful matrix mixer. There's now a new place to use units too, as the Audio Queue now offers developers a way to "tap" into the data being queued up for playback. To top it all off, a new "multi-route" system allows us to play out of multiple, multi-channel output devices at the same time.
Want to see, and hear, how all this stuff works? This section is the place to find out.