Analyzing the effects on the internal signal-to-noise ratio for bilateral hearing-aid systems configured for asymmetric processing

This paper investigates how bilateral hearing-aid systems configured to perform asymmetric processing affect the internal signal-to-noise ratio (SNR) in the auditory system. Here, an asymmetric hearing-instrument (HI) system is characterized by directional noise reduction in the instrument in one ear whereas the contra-lateral device is adjusted for omni mode processing. The Equalization and Cancellation model is used to evaluate the internal SNR of the auditory system. Two reference conditions were also created, a system with directionality in both HI, and one with omni-mode processing in both HI. A speaker was placed to the front, and another speaker was placed at the side. In the first experiment, the target was assumed to be in the front direction and the noise was assumed to be coming from the side. Here, it was shown that the asymmetric system provided the same SNR as the system with directionality in both HI. The noise and target positions were interchanged and the experiment was repeated. In this case, the asymmetric system provided similar SNR as the system with omni-mode processing in both HI, which for this test condition provided a better SNR than the system with directionality in both HI.