PurposeTo evaluate the test–retest reliability of a headphone-based spatial release from a masking task with two maskers (referred to here as the SR2) and to describe its relationship to the same test done over loudspeakers in an anechoic chamber (the SR2A). We explore what thresholds tell us about certain populations (such as older individuals or individuals with hearing impairment) and discuss how the SR2 might be useful in the clinic.MethodFifty-four participants completed speech intelligibility tests in which a target phrase and two masking phrases from the Coordinate Response Measure corpus (Bolia, Nelson, Ericson, & Simpson, 2000) were presented either via earphones using a virtual spatial array or via loudspeakers in an anechoic chamber. For the SR2, the target sentence was always at 0° azimuth angle, and the maskers were either colocated at 0° or positioned at ± 45°. For the SR2A, the target was located at 0°, and the maskers were colocated or located at ± 15°, ± 30°, ± 45°, ± 90°, or ± 135°. Spatial release from masking was determined as the difference between thresholds in the colocated condition and each spatially separated condition. All participants completed the SR2 at least twice, and 29 of the individuals who completed the SR2 at least twice also participated in the SR2A. In a second experiment, 40 participants completed the SR2 8 times, and the changes in performance were evaluated as a function of test repetition.ResultsMean thresholds were slightly better on the SR2 after the first repetition but were consistent across 8 subsequent testing sessions. Performance was consistent for the SR2A, regardless of the number of times testing was repeated. The SR2, which simulates 45° separations of target and maskers, produced spatially separated thresholds that were similar to thresholds obtained with 30° of separation in the anechoic chamber. Over headphones and in the anechoic chamber, pure-tone average was a strong predictor of spatial release, whereas age only reached significance for colocated conditions.ConclusionsThe SR2 is a reliable and effective method of testing spatial release from masking, suitable for screening abnormal listening abilities and for tracking rehabilitation over time. Future work should focus on developing and validating rapid, automated testing to identify the ability of listeners to benefit from high-frequency amplification, smaller spatial separations, and larger spectral differences among talkers.

Early reflections have been linked to improved speech intelligibility, while later-arriving reverberant sound has been shown to limit speech understanding. Here, these effects were examined by artificially removing either early reflections or late reflections. Removing late reflections improved performance more for colocated than for spatially separated maskers. Results of a multiple regression analysis suggest that pure-tone average (PTA) is a significant predictor of spatial release from masking (SRM) in all acoustic conditions. Controlling for the effects of PTA, age is a significant predictor of SRM only when early reflections are absent.

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Currently, there are many different laboratory-based tests of spatial release from masking (SRM) that use speech materials; however, there is still disagreement as to the impact of age and hearing loss on SRM. The time is ripe, then, for taking these tests out of the laboratory and testing larger numbers of listeners varying in age and hearing ability in order to provide the statistical power needed to answer the questions currently being asked. Unfortunately, most of the tests that have been developed are either open set, and thus require a tester to administer them, or require complex soundfield speaker arrays. Our laboratory has recently developed and verified an automated headphone-based test that can be presented in only five to ten minutes and that provides results that are predictive of results obtained in an anechoic chamber. The data associated with the verification of this test procedure will be presented.

The ability to understand speech in the presence of competing sound sources is essential to communication success. This task is difficult for listeners with healthy auditory systems, but becomes substantially more difficult as listeners age and experience various insults to the system. Our laboratory has developed a rapid, automated method of measuring the relative ability to perform a standard laboratory version of this task, which has been applied to a large set of spatial separations between 0 and 135 degrees, and a range of levels and bandwidths. Performance has been obtained in over 100 listeners varying in age and hearing ability between one and fifteen times over the course of four years. We have examined both the reliability of this test, by comparing how performance changed across test sessions with the same acoustical conditions (less than 1 dB on average), and the relative influences of age and hearing loss at various separations. Normative functions based on over 100 listeners are available for a colocated control condition, a spatial separation of 45 degrees, and the difference between the two (spatial release from masking). Normative functions take into account both age, between 18 and 80 years, and moderate hearing loss in the standard audiometric frequencies. A calibrated version of the test is freely available for use on an iPad.