Abstract: A system to automatically control the changeover of recording and recording stop, or transmission and transmission stop, and being employed in the recording or transmitting device provided with a vibration pick-up type microphone for picking up bone-conducted voice sounds. The automatic changeover of recording and recording stop or transmission and transmission stop is attained by control signals corresponding to impact vibrations except voice signals uttered by a microphone wearer himself, transmitted through his bones and picked up by the microphone or another controlling microphone.