Effects of Reverberation on the Relation Between Compression Speed and Working Memory for Speech-in-Noise Perception

Objectives: Previous study has suggested that when listening in modulated noise, individuals benefit from different wide dynamic range compression (WDRC) speeds depending on their working memory ability. Reverberation reduces the modulation depth of signals and may impact the relation between WDRC speed and working memory. The purpose of this study was to examine this relation across a range of reverberant conditions. Design: Twenty-eight older listeners with mild-to-moderate sensorineural hearing impairment were recruited in the present study. Individual working memory was measured using a Reading Span test. Sentences were combined with noise at two signal to noise ratios (2 and 5 dB SNR), and reverberation was simulated at a range of reverberation times (0.00, 0.75, 1.50, and 3.00 sec). Speech intelligibility was measured in listeners when listening to the sentences processed with simulated fast-acting and slow-acting WDRC conditions. Results: There was a significant relation between WDRC speed and working memory with minimal or no reverberation. Consistent with previous research, this relation was such that individuals with high working memory had higher speech intelligibility with fast-acting WDRC, and individuals with low working memory performed better with slow-acting WDRC. However, at longer reverberation times, there was no relation between WDRC speed and working memory. Conclusions: Consistent with previous studies, results suggest that there is an advantage of tailoring WDRC speed based on an individual's working memory under anechoic conditions. However, the present results further suggest that there may not be such a benefit in reverberant listening environments due to reduction in signal modulation. ACKNOWLEDGMENTS: The authors thank Tim Schoof for help with calibration, Laura Mathews and Melissa Sherman for assistance with participant recruitment, and Thomas Lunner for providing the Reading Span test. This research was funded by the National Institutes of Health Grants F31 DC015373 to P.R., R01 DC008168 to P.Z., and R01 DC006014 to P.S. The work presented in this manuscript represents an original contribution that has not been previously published or submitted for publication elsewhere. All authors contributed equally to this study. P.R. and P.S. collected and analyzed data and wrote the main article; P.Z. contributed to the study design and manuscript preparation. All authors discussed the results and implications and commented on the manuscript at all stages. The authors have no conflicts of interest to disclose. Address for correspondence: Pamela Souza, Department of Communication Sciences and Disorders, Northwestern University, 2240 E Campus Drive, Evanston, IL 60208, USA. E-mail: p-souza@northwestern.edu Received May 31, 2018; accepted November 26, 2018. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

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