Design and Implementation of a Novel Skull Vibration Sensing Module for Bone Conduction Microphone

This study presents a packaged MEMS acoustic or air pressure sensing module (Fig. 1) to detect the skull vibration for bone conduction microphone (BCM) application. The proposed microphone design has two merits: (1) the packaged module (Fig. 1) enable the skull vibration detection using the MEMS sensor; (2) no sound port is required to remove the environmental and wind noise and to avoid the damage from dust and water (Fig. 1a). The device with the dimensions of $3.5\times 2.65\times 1.48\ \text{mm}^{3}$ is implemented using the packaging and assembly of existing MEMS sensor with polymer diaphragm and metal proof-mass. Measurements show the device has a sensitivity of −39.1dB/g, $\text{THD} < 0.22\ \%$ at 1kHz, and ±5dB bandwidth for 100Hz∼6.7kHz. Frequency responses of different samples show good repeatability.