Basic perception and propagation characteristics of bone-conducted sounds presented to facial parts

Abstract

In conventional bone conduction (BC) devices, a vibrator is typically applied to the mastoid or condyle processes. Recently, however, BC-sound presentations to facial parts such as the nose have also been investigated. As the face is among the most complex structures in the human body, BC sounds presented to facial parts are likely to show different perception and propagation characteristics from those presented to conventional parts. We measured hearing thresholds, ear canal sound pressures in both ears, and head vibrations at both mastoid processes when BC sounds were presented to the facial (nasal, infraorbital region, zygomatic, jaw angle, and chin) and conventional (mastoid and condyle processes and forehead) parts of normal-hearing subjects. The results indicated that the facial parts and mastoid process had similar threshold characteristics. By changing the stimulus parts on the face, the hearing thresholds did not change, whereas the amplitudes of each propagation component changed significantly.