To evaluate the impact of the position of noise source(s) and reverberation on the directional benefit and performance of three commercially available directional hearing aids.
Directional benefit and performance were measured for four different configurations of competing noise source(s) in two different reverberant rooms. Three pairs of hearing aids representing three commercial models were selected based on electroacoustic evaluation of directivity. Directional benefit and performance of 25 subjects with symmetrical, sloping, sensorineural hearing loss were measured in all test environments using a modified version of the Hearing in Noise Test.
Both reverberation and configuration of the competing noise source(s) significantly affected directional benefit and performance. There was no significant correlation between directional benefit and directional performance. The order of benefit and performance across hearing aid brands (from best to worst) varied depending on the noise source configuration.
Data revealed increasing reverberation significantly decreased directional benefit and performance. The absolute and relative (rank ordering) directional benefit and performance varied across hearing aid brand, with noise source configuration. These results suggest that data collected in traditional test environments (e.g., a single competing noise placed at 180° azimuth) cannot be used to accurately predict directional benefit or performance in the majority of other test and real-world environments. The impact of reverberation and noise source configuration on directional benefit/performance can be explained fairly well by the interaction between the spatial properties of the noise source(s) and the polar directivity patterns of the hearing aids.