Zobel in Cognitive bag lunch Weds. Feb. 20 at noon

The next cognitive brown bag is on 2/20 (12:00, Tobin 521B). The speaker is Ben Zobel (UMass PBS); title and abstract are below. Please note that there is no cognitive brown bag on 2/27.

Effects of Age on Spatial Release from Informational Masking

Spatial release from informational masking (SRIM) describes the reduction in perceptual/cognitive confusion between relevant speech (target) and irrelevant speech (masker) when target and masker are perceived as spatially separated compared to spatially co-located. Under complex listening conditions in which peripheral (head shadow) and low-level binaural (interaural time differences) cues are washed out by multiple noise sources and reverberation, SRIM is a crucial mechanism for successful speech processing. It follows that any age-related declines in SRIM would contribute to the speech-processing difficulties older adults often report within noisy environments. Some research indicates age-related declines in SRIM (e.g., Gallun et al., 2013) while other research does not (e.g., Li et al., 2004). This talk will describe research designed to add clarity to two fundamental questions: 1) Does SRIM decline with age and, if so, 2) does age predict this decline independent of hearing loss? To answer these questions, younger and older participants listened to low-pass-filtered noise-vocoded speech and were asked to detect whether a target talker was presented along with two-talker masking babble. Spatial separation was perceptually manipulated without changing peripheral and low-level cues (Freyman et al., 1999). Results showed that detection thresholds were nearly identical across age groups in the co-located condition but markedly higher for older adults compared to younger adults when target and masker were spatially separated. Multiple regression analysis showed that age predicted a decline in SRIM controlling for hearing loss (based on pure-tone audiometry), while there was no indication that hearing loss predicted a decline in SRIM controlling for age. These results provide strong evidence that SRIM declines with age, and that the source of this decline may begin at higher perceptual/cognitive levels of auditory processing. Such declines are likely to contribute to the greater speech-processing difficulties older adults often experience in complex, noisy environments.