Spatial Release From Masking Using Clinical Corpora: Sentence Recognition In a Colocated or Spatially Separated Speech Masker

Abstract

Background: Speech recognition in complex multisource environments is challenging, particularly forlisteners with hearing loss. One source of difficulty is the reduced ability of listeners with hearing loss tobenefit from spatial separation of the target and masker, an effect called spatial release from masking(SRM). Despite the prevalence of complex multisource environments in everyday life, SRM is not routinelyevaluated in the audiology clinic.<br />Purpose: The purpose of this study was to demonstrate the feasibility of assessing SRM in adults usingwidely available tests of speech-in-speech recognition that can be conducted using standard clinicalequipment.<br />Research Design: Participants were 22 young adults with normal hearing. The task was masked sentencerecognition, using each of five clinically available corpora with speech maskers. The target alwayssounded like it originated from directly in front of the listener, and the masker either sounded like it originatedfrom the front (colocated with the target) or from the side (separated from the target). In the realspatial manipulation conditions, source location was manipulated by routing the target and masker toeither a single speaker or to two speakers: one directly in front of the participant, and one mountedin an adjacent corner, 90° to the right. In the perceived spatial separation conditions, the target andmasker were presented from both speakers with delays that made them sound as if they were eithercolocated or separated.<br />Results: With real spatial manipulations, the mean SRM ranged from 7.1 to 11.4 dB, depending on thespeech corpus. With perceived spatial manipulations, the mean SRM ranged from 1.8 to 3.1 dB. Whereasreal separation improves the signal-to-noise ratio in the ear contralateral to the masker, SRM in the perceivedspatial separation conditions is based solely on interaural timing cues.<br />Conclusions: The finding of robust SRM with widely available speech corpora supports the feasibility ofmeasuring this important aspect of hearing in the audiology clinic. The finding of a small but significantSRM in the perceived spatial separation conditions suggests that modified materials could be used toevaluate the use of interaural timing cues specifically.<br />