Individual differences in the acoustic properties of human skulls.

The acoustic properties of skulls and how they might affect hearing was investigated. Broadband noise was projected through the skull and spectrally analyzed using a Fast Fourier Transform and in 1/3-octave bands. Energetic peaks were found centered near 1050 and 4000 Hz, and troughs near 100 and 650 Hz, in addition to substantial individual differences (e.g., range greater than 29 dB around 900 Hz). Acoustic patterns from each skull were subsequently compared with air and bone conduction sensory thresholds. Individual skull patterns reliably correlated with bone conduction thresholds, but not air conduction thresholds, indicating a possible mediating role of the skull to hearing.