Spatial release from masking under reverberation (Viveros Muñoz et al., 2019)

Purpose: Normal-hearing and hard-of-hearing listeners suffer from reduced speech intelligibility in noisy and reverberant environments. Although daily listening environments are in constant motion, most researchers have only studied speech-in-noise perception for stationary masker locations. The aim of this study was to investigate the spatial release from masking (SRM) of circularly and radially moving maskers under different room acoustic conditions for young and elderly subjects.
Method: Twelve young subjects with normal hearing and 12 elderly subjects with normal hearing or mild hearing loss were tested. Several different room acoustic conditions were simulated and reproduced via headphones using binaural synthesis. The target speech stream consisted of German digit triplets, and masker stream consisted of quasistationary noise with matched long-term averaged speech spectra. During the experiment, the position of the masker was changed to be in different stationary positions, or varied continuously. In the latter case, it was moved either on a circular trajectory spanning a 90° azimuth angle or on a radial trajectory linearly increasing the distance to the receiver from 0.5 m to 1.8 m. Absorption characteristics of the virtual room’s surfaces were changed, recreating an anechoic room, a treated room with mean reverberation times (RT60) = 0.48 s, and an untreated room with mean RT60 = 1.26 s.
Results: For the circular condition, a significant difference was found between moving and stationary maskers, F(4, 44) = 20.91, p < .001, with a bigger SRM for stationary maskers than moving masker conditions. Also, both age groups displayed a significant decrease in SRM over the reverberation conditions: F(2, 22) = 12.24, p < .001.
For the radial condition, both age groups showed a significant decrease in SRM over the reverberation conditions, F(2, 22) = 13.62, p < .001, as well as the moving and stationary masker conditions, F(8, 88) = 29.23, p < .001. In general, the SRM of a moving masker decreased when the reverberation increased, especially for elderly subjects.
Conclusions: A radially moving masker led to improved SRM in an anechoic environment for both age groups, whereas a circularly moving masker caused degraded SRM, especially for elderly subjects in the highly reverberant environment.

Supplemental Material S1. Additional data for experiments on spatial release from masking in different room acoustic conditions.

Viveros Muñoz, R., Aspöck, L., & Fels, J. (2019). Spatial release from masking under different reverberant conditions in young and elderly subjects: Effect of moving or stationary maskers at circular and radial conditions. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2019_JSLHR-H-19-0092