Mechanisms of Bone-conducted Ultrasonic Perception Assessed by Measurements of Acoustic Fields in the Outer Ear Canal and Vibrations of the Tympanic Membrane

Bone-conducted ultrasound (BCU) is even perceived by the profoundly sensorineural deaf; however, the mechanisms involved remain unclear. Acoustic fields in the external auditory meatus and vibrations of the tympanic membrane (TM) under BCU stimulation were measured to examine the generation of audible subharmonics in the bone-conduction transmission pathway. In the results, no significant audible-frequency signals were observed. These findings indicate that nonlinear distortions do not contribute to BCU perception and specific properties of BCU perception may be related to mechanisms in the cochlea or afferent neural pathway.