Probe tube systems: Effects of equalization method on measurement of hearing aid output
Abstract
A soundfield equalization method will determine the reference value used to compute measured hearing aid output. Several equalization methods can be used with probe tube systems. This study was designed to determine the effects of three equalization methods on insertion and insitu gain for an open mold and closed mold condition while varying ear canal circumference. Twelve subjects were selected to represent a wide range of ear canal circumferences. Measures of insertion and insitu gain were obtained using an occluding earmold and a tube fitting. All measures were obtained according to three soundfield equalization methods, substitution, pressure, and ipsilateral comparison. Repeated-measures ANOVAS performed on measured hearing aid output for the three equalization methods revealed significant differences (p $<$ 0.01) for insertion and insitu gain. ANCOVAS performed on canal circumference and open mold insertion gain reveal a strong negative correlation. The differences obtained in measured hearing aid output for the three equalization methods are due to the inclusion and exclusion of different acoustical components for each method. The strong negative correlation between canal circumference and insertion gain is due to placement of the reference microphone in combination with the equalization method utilized. The results indicate that the method of equalization should be considered when interpreting results for insertion and insitu gain. Also, canal circumference and degree of ear canal occlusion influence measured hearing aid output and should be considered when fitting a hearing aid.
Degree
Ph.D.
Advisors
Goldstein, Purdue University.
Subject Area
Audiology|Biomedical research
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