conflict problem??

[Georg]

NSURL *url = [NSURL fileURLWithPath:@"/dev/null"];

NSDictionary *settings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
[NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
[NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
[NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey,
nil];

NSError *error;

recorder = [[AVAudioRecorder alloc] initWithURL:url settings:settings error:&error];


if (recorder) {
[recorder prepareToRecord];
recorder.meteringEnabled = YES;
[recorder record];
levelTimer = [NSTimer scheduledTimerWithTimeInterval: 0.03 target: self selector: @selector(levelTimerCallback userInfo: nil repeats: YES];

I use a timer for detecting the lowPassResults from microphone, timer interval is 0.03.

if I remarked below section, then I can hear the bubble sound.

if (recorder) {
[recorder prepareToRecord];
recorder.meteringEnabled = YES;
[recorder record];
levelTimer = [NSTimer scheduledTimerWithTimeInterval: 0.03 target: self selector: @selector(levelTimerCallback userInfo: nil repeats: YES];

does it mean that I can not play the sound effect during a microphone detection