How Do I do Real Time Sound/Signal Processing On The iPhone?

Question

I may be doing an iPhone-based application doing near-real-time sound-processing (filtering, etc). I was wondering the best way to get started. Would I want to create an audio cue for recording and processing sound, as described here?

Edit:

I should be clear. I am not asking how to do signal processing, in general. I know some of that and my team's expert will handle the rest. I asking what the "low level" interfaces to sound data on the iphone are.

Edit2:

My iphone development has been pushed back a week or two so I don't have access to the deve kit right now. Once I have access to the kit, I'll mark one answer or another correct.

Answer 1

Sound processing is a big subject. AudioQueue will get you the raw data. Apple provides two samples that will get you started using AudioQueue: SpeakHere and AurioTouch.

Answer 2

I used SpeakHere as a starting point for some audio processing I wanted to do. It's relatively easy to understand, and has all the pieces to do input and output.