Bone-conduction propagation in the human body: implications for high-frequency therapy.

We assessed ultrasonic transmission in a dry skull; in a dry skull with water, simulating the living condition; in a cadaver head; and in six human subjects, one of whom exhibited no measurable hearing. By using these preparations, we concluded that fluid conduction is essential in the propagation of sound across the head, whereas the bone pathway is far less effective in that regard. Thus, there is little ear isolation beyond 10 dB even up to 80 kHz, extending the masking dilemma in cases of unilateral hearing loss.