Transient acceleration response of a bone-conducted ultrasonic pulse in living human head

Ultrasonic hearing through bone-conduction is referred to as bone-conducted ultrasound (BCU). Because the perceptual mechanisms of ultrasonic hearing are still unclear, it is necessary to approach the subject from various aspects to clarify such mechanisms; the propagation process of ultrasonic vibration in the head is one of them. To estimate propagation pathways and modes of BCU in living human head, we measured the transient acceleration responses for ultrasonic pulses. The acceleration responses were obtained at the left and right ears simultaneously for left-side, right-side and forehead excitations. Transient responses show that there are several transmission pathways or modes, and the dominant pathways of BCU were identified.