Android - can I mute currently playing audio applications?
AudioManager.setStreamSolo(AudioManager.STREAM_VOICE_CALL, true);
다음과 같은 걸 고려해볼수도 있다.
AudioManager audioMan =
(AudioManager) getSystemService(Context.AUDIO_SERVICE);
audioMan.adjustVolume(AudioManager.ADJUST_LOWER,
AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE);