How to do real-time audio processing / signal processing on iPhone?

Question

I can make an iPhone based application that does real-time audio processing (filtering, etc.). I was wondering how to get started. I would like to create an audio signal for recording and processing sound, as described here ?

Edit:

It should be clear to me. I do not ask how to do signal processing at all. I know that some of them and my expert team will cope with the rest. I ask what “low” means for audio data on iphone.

Edit2:

My iphone development was dropped after a week or two, so I don't have access to the deve kit right now. As soon as I have access to the set, I mark one answer or the other correct.

Answer 1

Sound processing is a big question. AudioQueue will provide you with raw data. Apple provides two samples to help you get started with AudioQueue: SpeakHere and AurioTouch.

Answer 2

I used SpeakHere as a starting point for some sound processing that I wanted to do. It is relatively easy to understand and has all the parts for input and output.