Date of Award

5-1962

Degree Name

Master of Arts

Department

Speech Pathology and Audiology

Access Setting

Masters Thesis-Open Access

Abstract

The purpose of this study was to investigate the upper pitch limits of hearing in young children as a test of a hypothesis proposed by Fatsinger (1959).

According to the place theory of hearing, the low pitch sounds are located at the apex or wide part of basilar membrane, and are mediated by the long fibers, and the high pitch sounds at the basal or narrow part of the basilar membrane, and are mediated by the short fibers. Therefore, a size change which involved the basilar membrane could cause a shit in the pitch sensitivity range by producing longer fibers and a loss of short fibers.

If the size change hypothesis is correct, the younger child with smaller inner ear structures should respond to a higher pitch range. As the child matures, and his inner ear grows larger, his pitch range should become lower. Theoretically, this process should occur during early childhood and by the time the child has reached his fifth or sixth year his hearing should be in the normal pitch range.

Bast and Anson (1949) have shown that the temporal bone is fully developed at birth, and that no significant growth of this bone occurs as the child matures. However, this would not necessarily mean that the membranous structures within the bone do not exhibit growth after birth. Since it is recognized that the eye structures exhibit growth during the early years of life, it would seem reasonable that the inner ear structures might also demonstrate some growth. A search of the literature has failed to find any specific information concerning the growth of the inner ear structures.

Through the application of psychogalvanic skin resistance audiometry adapted for the testing of upper pitch sensitivity, it should be possible to plot the upper pitch limits of young children of various ages, and to compare these results to see if they substantiate the foregoing hypothesis.

If Fatsinger’s hypothesis is supported, it could add significantly to our understanding of the hearing of young children and could be useful in the formation of new hypotheses, particularly since present auditory theory does not adequately deal with the upper pitch limits of children. This study could also be useful as a further evaluation of psychogalvanic skin resistance audiometry as applied to young children.

This study was planned as a pilot study. Since a thorough investigation of a hypothesis of this magnitude would require a great deal of money and technical skill, the main purposes of this study were to ascertain the feasibility of such a study and to investigate some of the problems which might be encountered.

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