Binaural masking release: An increase in workload capacity

Abstract

The following study applied reaction time analyses of workload capacity to tone-in-noise detection for monaural (NmSm), diotic (tone and noise identical at each ears; NoSo), and dichotic (tone is anti-phase but noise is not; NoSTT) conditions. Reaction times allow comparisons between these conditions at the same signal-to-noise ratios (something which cannot often be done using threshold and percent correct) and can also expose dynamic contributions to the release from masking provided by binaural interactions. Here, we apply a reaction-time based capacity coefficient, which provides an index of workload efficiency. We demonstrate that the release from masking generated by the addition of an identical stimulus to one ear (NmSm vs. NoSo) is unlimited capacity (efficiency ≈1), consistent with an independent parallel-channel model. However, the release from masking generated by the anti-phasic tone (NoSo vs. NoSTT) leads to a significant increase in workload capacity (increased efficiency)—most specifically at lower signal-to-noise ratios. These experimental results provide further evidence that configural processing plays a critical role in binaural masking release, and that these mechanisms operate more strongly when the signal stimulus is difficult to detect.