iOS Sound Manipulation with NSData *

[nightwar00]

Hi there, I'm new and my english is very poor so don't be cruel

I have a little problem with an application i have to do. I try to make some effects on sound i have but i can't found any API to do that. The OpenAL API don't handle distorsion and reverb. So i try to make it programmaticaly.

I open a sound with initWithData (i put my little code after) and i try to change somme value in the mutableArray, but when i change one value, the sound don't play .

NSMutableData *soundFileData;
	soundFileData = [NSMutableData dataWithContentsOfURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"A2.wav" ofType:NULL]]];
	
	
	((char *)[soundFileData mutableBytes])[1] = 73;
	NSLog(@"%d",((char *)[soundFileData mutableBytes])[1]);
	AVAudioPlayer *myPlayer = [[AVAudioPlayer alloc] initWithData:soundFileData error:NULL];

	[myPlayer prepareToPlay]; 
	[myPlayer play];

So when i assign 73 to the mutableArray , everything gonna be alright (because it is the previous value on the array) but if i put 72 or any other value , nothing append when i play the sound. So 2 question for you

1) why no sound appears when i assign an other value on it?
2) how can i implement effects like distorion or reverb on a file that already exist?

Please help me i'm searching but i can't found any solution....

If you know an API that manipulate data sound easily (and where we can do everything we want) i thank you so much.

Thank you for any answer and again sorry for my english....