Can someone help me use the AudioQueue services on the iPhone to play a certain frequency (say, 440 Hz)? I've looked at the documentation, but I can't seem to figure out quite how to do it. Apple's sample code also isn't helping me too much.
Thanks!
ok, this is kinda lame, but if no one comes up with the real answer, you could just pre-record a sine wave and loop it. If it's cut well, it should play just fine. Of course this response would only work if you had only a few different frequencies to play.
/Developer/Examples/CoreAudio/SimpleSDK/DefaultOutputUnit has a sample of how to play a tone at a given frequency and sample rate.
I basically copied the code (also using a bit from this blog entry) and it worked with basically no change on the iPhone.
It isn't hard at all to do this. Take a look at the AudioQueue examples. If you look at the code to play back an audio file, you're going to just do that, except without actually reading a file.
You just divide the sampling rate by your frequency, calculate a sine wave, and feed those values into the audioqueue in your playback callback function.