A NOVEL ALL SILICON BONE CONDUCTION MICROPHONE WITH BROAD BANDWIDTH (100Hz∼10kHz)

This study designs and realizes a MEMS spring-mass system to detect vocal cord vibration transmitted through skull and muscle that can be applied for bone conduction microphone (BCM) application. The BCM with no sound-port has the advantage to receive only own voice and could remove the environmental/wind noise. The proposed BCM design has three merits: (1) the spring-mass structure design could achieve 10kHz bandwidth to captures broad frequency responses; (2) the dimple stopper design is exploited to limit the upper and lower displacement of the moving diaphragm for reliability enhancement, (3) compared with existing BCM, the presented one is implemented using only wafer processes with no assembly required. The device after metal-can packaging has the dimensions of 4x3x0.9 mm(3). Measurements indicate the device has a sensitivity of -34.5dBFS/g at 1kHz, and flat bandwidth(+/- 3dB) for 100Hz similar to 10kHz. The proposed BCM assembled on earphone demonstrates that the recording quality is excellent for voice call communication, and it records user's own voice only without any audio algorithm processing.