Adapting bilateral directional processing to individual and situational influences

This study examined differences in benefit from bilateral directional processing. Groups of listeners with symmetric or asymmetric audiograms <2 kHz, a large spread in the binaural contribution to speech-in-noise reception (BILD), and no difference in age or overall degree of hearing loss took part. Aided speech reception was measured using virtual acoustics together with a simulation of a linked pair of hearing aids. Five processing schemes and three acoustic scenarios were used. The processing schemes differed in the tradeoff between signal-to-noise ratio (SNR) improvement and binaural cue preservation. The acoustic scenarios consisted of a frontal target talker and two lateral speech maskers or spatially diffuse noise. For both groups, a significant interaction between the BILD, processing scheme, and acoustic scenario was found. This interaction implied that, for lateral speech maskers, users with BILDs >2 dB profit more from low-frequency binaural cues than from greater SNR improvement, whereas for smaller BILDs the opposite is true. Audiometric asymmetry reduced the BILD influence. In spatially diffuse noise, maximal SNR improvement was beneficial. Moreover, binaural tone-in-noise detection (N₀S_π threshold) at 500 Hz predicted benefit from low-frequency binaural cues. These results provide a basis for adapting bilateral directional processing to the user and the scenario.