LINEARITY OF SOUND-TRANSMISSION THROUGH THE HUMAN SKULL IN-VIVO

The linearity of sound propagation through the human skull was investi gated. One male subject, equipped with bilateral skin-penetrating tita nium fixtures for attachment of bone-anchored hearing aids, was studie d thoroughly. Three different methods were used: comparison of the fre quency response functions estimated at different signal levels (using stepped sine as well as random noise), comparison of the coherence fun ction at different signal levels (using random noise), and the Hilbert transform of the estimated frequency response function. Frequencies f rom 0.1 to 10 kHz and signal levels up to 77 dB HL at discrete frequen cies were used. No indication of any significant nonlinear behavior wa s found with the three methods used. (C) 1996 Acoustical Society of Am erica.