Lateralization of bone-conducted sounds.
Lateralization of bilaterally applied bone-conducted signals could be accomplished by variation of time (delta t) or intensity (delta I) differences between signals. The task was relatively easy with clicks and with tone pips with short rise times. When rise times were made longer than 1 msec the ability to localize deteriorated, indicating that it depended, within limits, on the steepness of the signal wavefront. Consequently, localization of continuous, pure-tone signals was much more difficult. It improved, with training, after subjects noticed small loudness increments on the side of the leading signal as soon as the phase between signals (delta phi) deviated from zero. Thus, localization of pure-tone signals was aided both by delta phi and delta I. The loudness increments were found to be caused by mechanical interference of ipsi- and contralateral signals at each cochlea, a type of interference peculiar to bone-conducted signals. There were also indications of slight degrees of neural interaction (mutual masking) so long as delta t between short-lasting signals was near zero. The tactile input at the point of contact between vibrators and skin did not significantly contribute to lateralization of bone-conducted signals.
D001301:Audiometry, Pure-Tone; D001307:Auditory Perception / Q000502:physiology*; D001844:Bone Conduction; D003051:Cochlea / Q000502:physiology; D006801:Humans; D008416:Mastoid / Q000502:physiology; D013017:Sound Localization / Q000502:physiology*; D014732:Vibration