Study on suppression effect of air-conducted sound by bone-conducted sound

This paper proposes a method for suppressing air-conducted (AC) sound by presenting bone-conducted (BC) sound. First, the amplitude and phase of BC tones at six frequencies (250, 500, 1000, 2000, 4000, and 8000 Hz) were examined by using a method of limits to suppress AC tones presented via earphones. On the basis of the results of the first experiment, finite-impulse-response (FIR) filters, dependent upon participants, were then designed as "a compensation filter" to cancel out AC sound by presenting BC sound. Next, whether or not AC complex tones presented via earphones could be suppressed by simultaneously presenting BC complex tones compensated for by FIR filtering was investigated. Finally, whether or not this method could be applied to suppress stationary noise was also investigated. From these investigations, the proposed method was found to adequately suppress AC complex tones, and the average amounts of suppression for the AC and AC complex tones were approximately 5 and 1 dB, respectively. In addition, it was also shown that the proposed method can be used to suppress AC stationary noise but not greatly.