Adaptive Directional Benefit in the Near Field: Competing Sound Angle and Level Effects

ABSTRACT

Two experiments were performed that examined adaptive directional benefit and directional benefit as a function of competing noise level. Fourteen bilaterally fitted adult listeners with sloping, sensorineural hearing loss participated in both experiments. The results of the first experiment provide additional support for an adaptive advantage in environments with a discrete competing noise source placed near the listener. This advantage occurs even if the noise source is moving and only is present when the angle of the noise source relative to the listener does not correspond to an angle for which the fixed directional mode is optimized. Speech transmission index (STI) calculations do not generally support adaptive directional benefit in the presence of multiple competing noise sources. Specifically, an adaptive advantage was measured using the STI only when the intensity level of one of the competing noise sources in a group was at least 12 to 15 dB greater than all other sources combined. The results of the second experiment revealed more directional benefit for poorer signal-to-noise ratios (SNRs). However, if the SNR was held constant, the absolute noise level did not affect the magnitude of directional benefit.

KEYWORDS

Directional hearing aids - adaptive directional microphones - directional benefit

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