a phone call when i'm using this app, and return to the app , the micro phone can not work properly.

Dear sir

I'm developing an android app with AIR，and there is a function 'microphone testing' in this app.

every time i answser a phone call when i'm using this app, and return to the app , the micro phone can not work properly.

_microphone = Microphone.getEnhancedMicrophone();

_microphone.setUseEchoSuppression(true);

_microphone.codec = SoundCodec.SPEEX;

_microphone.encodeQuality = 6;

_microphone.setLoopBack(true);

_microphone.noiseSuppressionLevel=-30

_microphone.setSilenceLevel(0,2000);

_microphone.gain = 80;

i tried to speak to the microphone , but no voice was detected and recorded.