Bone-Conduction Sensitivity along with Static Force, Location, and Stimulus

Abstract

This study sought to estimate bone-conducted hearing sensitivity as static force levels of the oscillator as well as identify the most sensitive bone-conducted location on the human head when stimulated by tone and speech stimuli. In Experiment I, 24 young normal hearing listeners responded to bone-conducted thresholds ranging from 250 to 8,000 Hz in three placement locations: the forehead and the left and right mastoids. At each location and across all participants, the static force applied to various forces related to the individual’s head size (i.e., Hooke’s raw). The results of this experiment indicated that increased static force would not significantly cause more sensitive (or lower) thresholds. Thresholds of the forehead placement were less sensitive than both mastoids. Experiment II involved 24 young normal hearing listeners to determine the bone-conducted hearing thresholds at five placements (i.e., condyle, jaw angle, mastoid, temple, vertex) of the head, using tones ranging from 500 to 6,000 Hz and spondee words. The results indicated that the condyle and vertex are the most and least sensitive placements, respectively, regardless of tone and speech stimuli. Such information may be extended to future series of studies related to develop effective bone-conduction communication devices under harmful noisy conditions as well as contribute to the development of a computational model of bone-conducted sound transmission pathways in the human skull.