Glimpsing keywords across sentences in noise: A microstructural analysis of acoustic, lexical, and listener factors.

Abstract

This study investigated how acoustic and lexical word-level factors and listener-level factors of auditory thresholds and cognitive-linguistic processing contribute to the microstructure of sentence recognition in unmodulated and speech-modulated noise. The modulation depth of the modulated masker was changed by expanding and compressing the temporal envelope to control glimpsing opportunities. Younger adults with normal hearing (YNH) and older adults with normal and impaired hearing were tested. A second group of YNH was tested under acoustically identical conditions to the hearing-impaired group, who received spectral shaping. For all of the groups, speech recognition declined and masking release increased for later keywords in the sentence, which is consistent with the word position decreases in the signal-to-noise ratio. The acoustic glimpse proportion and lexical word frequency of individual keywords predicted recognition under different noise conditions. For the older adults, better auditory thresholds and better working memory abilities facilitated sentence recognition. Vocabulary knowledge contributed more to sentence recognition for younger than for older adults. These results demonstrate that acoustic and lexical factors contribute to the recognition of individual words within a sentence, but relative contributions vary based on the noise modulation characteristics. Taken together, acoustic, lexical, and listener factors contribute to how individuals recognize keywords during sentences.