Date of Award

Spring 2012

Document Type


Degree Name

Doctor of Audiology (AuD)


School of Communication

First Advisor

Melinda F. Bryan


The present study investigated the effects of asymmetric directional microphone fittings on participants' acceptance of background noise and speech understanding in noise abilities. Thirteen adult, bilateral hearing aid users or non-hearing aid users with bilateral asymmetrical sensorineural hearing loss were fit binaurally with four different microphone conditions (i.e., bilateral omnidirectional, asymmetric directional poorer ear, asymmetric directional better ear, and bilateral directional) and monaurally with two microphone conditions (i.e., unilateral directional better ear and unilateral omnidirectional better ear). The amplification used was a pair of Siemens Intuis directional behind-the-ear hearing aids and comply earmolds.

The results indicated speech understanding in noise abilities are enhanced when fit with an asymmetric directional better ear microphone fitting (i.e., directional microphone on the better ear and omnidirectional microphone on the poorer ear) or bilateral directional microphone fitting as compare to a bilateral omnidirectional microphone fitting. In the monaural conditions, speech understanding in noise ability improved when using a unilateral directional microphone as compared to a unilateral omnidirectional microphone (Note: For the monaural conditions, the directional microphone was coupled to the better ear and poorer ear was plugged). Next, speech understanding in noise ability is not affected when utilizing a unilateral directional microphone fitting as compared to an asymmetric directional better ear microphone configuration.

The results further revealed that acceptance of background noise was similar for all microphone configurations (i.e., bilateral omnidirectional, asymmetric directional poorer ear, asymmetric directional better ear, or bilateral directional) for listeners with asymmetric hearing loss. "These results indicate that willingness to accept background noise is unchanged in the binaural microphone conditions. When comparing the monaural fitting conditions, the unilateral directional fitting provided significantly greater acceptance of background noise compared to the unilateral omnidirectional microphone fitting, indicating a person is more willing to accept background noise (i.e., more willing to wear hearing aids) with a unilateral directional microphone versus a unilateral omnidirectional microphone. Therefore, when considering a monaural hearing aid fitting a directional microphone should be considered. When comparing the binaural asymmetric directional better ear condition to the monaural directional microphone condition, there was difference in a person's willingness to accept background noise. Therefore, a person's willingness to wear amplification would be unaffected when fit monaurally or binaurally, as long a directional microphone is on the better ear.