Analysis of Earbud-Mounted Bone-Conduction Microphones

Bone-conduction microphones (BCMs) capture the wearer’s voice as vibrations of the body, and are therefore robust against environmental and wind noise. Employing BCMs can increase speech enhancement performance. Modern earbuds can be equipped with BCMs, presenting the opportunity to significantly improve the quality of the wearer’s voice for the far end. However, it is yet unclear how to optimally capture bone-conducted (BC) speech at the earbud. In this paper, we explore this question by comparing different earbuds based on measurements. We observed a similar sensitivity towards BC speech for all earbuds, with minor differences in bandwidth. This indicates that the choice of earbud has a small effect on the quality of the captured BC signal. Furthermore, we could identify a dominant vibration direction for every earbud and side, suggesting that it is sufficient to record the vibration in one spatial axis in practice.