On frequency characteristics of bone conduction actuators by measuring loudness, acceleration and otoacoustic emission

Bone conduction is being utilized widely for music reproduction and hearing aids. However, due to unclear transmitting process of bone conduction, some detailed characteristics are still in discussion. Previous researchers has made achievements on frequency characteristics of bone conduction actuators by comparing the relationship between loudness as a subjective measurement and acceleration as an objective measurement. In this paper, besides discussion on the possibility of estimating loudness characteristics on bone conduction actuators by means of acceleration, another method that uses otoacoustic emissions(OAEs) to estimate frequency characteristics of bone conduction is also presented. OAEs, which are acoustical signals considered to be from cochlea, are measurable of most humans with normal hearing. By giving a single stimulus to cochlea, otoacoustic emission will be transmitted into ear canal. According to the results, the emitted signal arose in response to the stimulus which was from a bone conduction actuator. It was found that similar emissions were responded to stimulus of bone conduction at the same frequency. It suggests possibility of using otoacoustic emission as a method for measuring frequency characteristics of bone conduction actuators.