Auditory Verbal Working Memory as a Predictor of Speech Perception in Modulated Maskers in Listeners With Normal Hearing

Purpose Background noise can interfere with our ability to understand speech. Working memory capacity (WMC) has been shown to contribute to the perception of speech in modulated noise maskers. WMC has been assessed with a variety of auditory and visual tests, often pertaining to different components of working memory. This study assessed the relationship between speech perception in modulated maskers and components of auditory verbal working memory (AVWM) over a range of signal-to-noise ratios. Method Speech perception in noise and AVWM were measured in 30 listeners (age range 31–67 years) with normal hearing. AVWM was estimated using forward digit recall, backward digit recall, and nonword repetition. Results After controlling for the effects of age and average pure-tone hearing threshold, speech perception in modulated maskers was related to individual differences in the phonological component of working memory (as assessed by nonword repetition) but only in the least favorable signal-to-noise ratio. The executive component of working memory (as assessed by backward digit) was not predictive of speech perception in any conditions. Conclusions AVWM is predictive of the ability to benefit from temporal dips in modulated maskers: Listeners with greater phonological WMC are better able to correctly identify sentences in modulated noise backgrounds. </jats:sec

Phonetic categorization and discrimination of voice onset time under divided attention

Event durations are perceived to be shorter under divided attention. “Time shrinkage” is thought to be due to rapid attentional switches between tasks, leading to a loss of input samples, and hence, an under-estimation of duration. However, few studies have considered whether this phenomenon applies to durations relevant to time-based phonetic categorization. In this study, participants categorized auditory stimuli varying in voice onset time (VOT) as /ɡ/ or /k/. They did so under focused attention (auditory task alone) or while performing a low-level visual task at the same time (divided attention). Under divided attention, there was increased response imprecision but no bias toward hearing /ɡ/, the shorter-VOT sound. It is concluded that sample loss under divided attention does not apply to the perception of phonetic contrasts within the VOT range

How does cognitive load influence speech perception? : An encoding hypothesis

Two experiments investigated the conditions under which cognitive load exerts an effect on speech perception. These experiments extend earlier research by using a different speech perception task (four-interval oddity task) and by implementing cognitive load through a task often thought to be modular, namely, face processing. In the cognitive-load conditions, participants were required to remember two faces presented before the speech stimuli. In Experiment 1, performance in the speech-perception task under cognitive load was not impaired in comparison to a no-load baseline condition. In Experiment 2, we modified the load condition minimally such that it required encoding of the two faces simultaneously with the speech stimuli. As a reference condition, we also used a visual search task that in earlier experiments had led to poorer speech perception. Both concurrent tasks led to decrements in the speech task. The results suggest that speech perception is affected even by loads thought to be processed modularly, and that, critically, encoding in working memory might be the locus of interference

Is the superior verbal memory span of Mandarin speakers due to faster rehearsal?

It is well established that digit span in native Chinese speakers is atypically high. This is commonly attributed to a capacity for more rapid subvocal rehearsal for that group. We explored this hypothesis by testing a group of English-speaking native Mandarin speakers on digit span and word span in both Mandarin and English, together with a measure of speed of articulation for each. When compared to the performance of native English speakers, the Mandarin group proved to be superior on both digit and word spans while predictably having lower spans in English. This suggests that the Mandarin advantage is not limited to digits. Speed of rehearsal correlated with span performance across materials. However, this correlation was more pronounced for English speakers than for any of the Chinese measures. Further analysis suggested that speed of rehearsal did not provide an adequate account of differences between Mandarin and English spans or for the advantage of digits over words. Possible alternative explanations are discussed