Characterization of human head vibration with bone-conducted ultrasonic stimulation

A novel hearing aid system based on bone-conducted ultrasonic (BCU) hearing is being developed for use by profoundly deaf people. However, the perception mechanisms involved in BCU hearing remain unclear. In this study, the way in which the mechanical frequency characteristics of human head vibration under BCU stimulation contribute to the hearing process was considered and examined in terms of the effects of the elasticity of the surface tissue that was in contact with a bone conduction vibrator. The results suggest that head vibration under BCU stimulation has low-pass filter-type characteristics with a cut-off frequency of between 30 and 40 kHz, which is attributed to the effects of the elasticity of living human skin. However, the issue of the psychoacoustic characteristics of the BCU hearing process not necessarily reflecting the mechanical frequency characteristics of head vibration remains. (C) 2014 The Japan Society of Applied Physics