当状态改变时，如何关闭MediaRecorder播放的声音

My Android application uses MediaRecorder on a SurfaceHolder to show a live preview of what the camera is capturing. Every time the user presses the REC button on the app, the app starts to record. Every time the state of the MediaRecorder switches to/from 'start', Android automatically (?) fires off a beep. This beep sounds different from phone to phone, which makes me think that this beep is natively attached to the state change of MediaRecorder. The beep is not played if the volume of the phone is set to silent.My Android application uses MediaRecorder on a