The effect of interaural electroacoustic hearing aid properties on sound localization abilities in normal and hearing-impaired listeners

The use and benefit of binaural amplification in the hearing impaired has generated considerable conflict. One easily measured benefit of binaural hearing includes improved sound localization. The normal binaural auditory system has the capacity to determine with considerable accuracy the azimuth of a sound source. Binaural hearing aid fitting procedures are typically accomplished with an independent concern for each ear. The interaural intensity, phase characteristics, and time of arrival cues processed by hearing aids undoubtedly affect the quality of the binaural fitting, The purpose of this study was to investigate the dependence between binaural hearing aids and in their electroacoustic functioning by determining minimal audible angles (MAA) and center position (CP) shifts in a sound localization task. Six normal and two hearing-impaired adults responded to tonal and click stimuli using four selected pairs of hearing aids. These pairs were selected for matched electroacoustic characteristics: interaural phase distortion, and interaural transient distortion. Results of this study revealed smaller MAAs and CP shifts with the hearing aid pair matched closely in electroacoustic characteristics, whereas dissimilar pairs had larger MAAs and greater CP shifts. The results of this study provide information concerning binaural interactions and hearing aid fitting procedures with implications for improved binaural hearing in the hearing impaired.