Vibration characteristics of bone conducted sound in vitro

A dry skull added with damping material was used to investigate the vibrato ry pattern of bone conducted sound. Three orthogonal vibration responses of the cochleae were measured, by means of miniature accelerometers, in the f requency range 0.1-10 kHz. The exciter was attached to the temporal, pariet al, and frontal bones, one at the time. In the transmission response to the ipsilateral; cochlea, a profound low frequency antiresonance (attenuation) was found, verified psycho-acoustically, and shown to yield a distinct lat eralization effect. It was also shown that, for the ipsilateral side, the d irection of excitation coincides with that of maximum response. At the cont ralateral cochlea, no such dominating response direction was found for freq uencies above the first skull resonance. An overall higher response level w as achieved, for the total energy transmission in general and specifically for the direction of excitation, at the ipsilateral cochlea when the transd ucer was attached to the excitation point closest to the cochlea. The trans ranial attenuation was found to be frequency dependent, with values from -5 to 10 dB for the energy transmission and -30 to 40 dB for measurements in a single direction, with a tendency toward higher attenuation at the higher frequencies. (C) 2000 Acoustical Society of America. [S0001-4966(00)01601- 5].