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Date of Award

Spring 2007

Document Type

Thesis - Open Access

Degree Name

Master of Science in Human Factors & Systems

Department

Human Factors and Systems

Committee Chair

Maranda McBride, Ph.D.

Committee Member

John French, Ph.D.

Committee Member

John Johnson, Ph.D.

Abstract

Two experiments were conducted to see if gender differences exist in bone conduction hearing processes. The first experiment was a pure tone study where hearing thresholds for six pure tone frequencies and four bone conduction skull locations were measured in 15 male and 15 female participants to determine if gender differences exist in auditory signal detection. As frequency of the pure tone signal increased the difference between genders’ hearing thresholds and mean ranks of threshold overall; however, when Kruskal-Wallis statistical tests were performed, significant differences between genders for bone conduction were only found for the mastoid location at 6000-Hz and 9000-Hz. Significant differences between skull locations were also detected over all six frequencies with the condyle location providing the lowest threshold overall.

The second experiment was a speech intelligibility study where one male and one female speakers’ voices were tested on two bone conduction locations on the head (condyle and mastoid) at four levels of pink background noise (0 dB, 83 dB, 93 dB, and 103 dB). The performance measure used in this study was accuracy based upon responses to the Modified Rhyme Test (MRT), where accuracy was measured by the total number of target words identified correctly out of 50. The target words were contained in carrier sentences presented in either the male or female voice. Six males and six females were tested and repeated measures ANOVA was used to analyze the data. The results showed the male and female voice to be equivalent in number of correct responses under the 0 dB pink noise condition, however, the male speaker’s voice and the condyle location provided a greater number of correct responses on the MRT when 93 and 103 dB of background noise was present.

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