Associations between speech understanding and auditory and visual tests of verbal working memory: effects of linguistic complexity, task, age, and hearing loss.

Sherri L. Smith,M. Kathleen Pichora-Fuller

doi:10.3389/fpsyg.2015.01394

Abstract

Listeners with hearing loss commonly report having difficulty understanding speech, particularly in noisy environments. Their difficulties could be due to auditory and cognitive processing problems. Performance on speech-in-noise tests has been correlated with reading working memory span (RWMS), a measure often chosen to avoid the effects of hearing loss. If the goal is to assess the cognitive consequences of listeners’ auditory processing abilities, however, then listening working memory span (LWMS) could be a more informative measure. Some studies have examined the effects of different degrees and types of masking on working memory, but less is known about the demands placed on working memory depending on the linguistic complexity of the target speech or the task used to measure speech understanding in listeners with hearing loss. Compared to RWMS, LWMS measures using different speech targets and maskers may provide a more ecologically valid approach. To examine the contributions of RWMS and LWMS to speech understanding, we administered two working memory measures (a traditional RWMS measure and a new LWMS measure), and a battery of tests varying in the linguistic complexity of the speech materials, the presence of babble masking, and the task. Participants were a group of younger listeners with normal hearing and two groups of older listeners with hearing loss (n = 24 per group). There was a significant group difference and a wider range in performance on LWMS than on RWMS. There was a significant correlation between both working memory measures only for the oldest listeners with hearing loss. Notably, there were only few significant correlations among the working memory and speech understanding measures. These findings suggest that working memory measures reflect individual differences that are distinct from those tapped by these measures of speech understanding.

Highlights

For over a half century, researchers and clinicians have recognized that speech understanding difficulties are common amongst older listeners, when speech is presented in a noisy background or when listeners have age-related hearing loss (e.g., Bocca and Calearo, 1963; Frisina and Frisina, 1997; Gates and Mills, 2005; Mills et al, 2006; Humes and Dubno, 2010)
The data showed that all participants had better performance with the auditory Word Auditory Recognition and Recall Measure (WARRM) test than with the visual Reading Span (RS) test, most likely because the WARRM sentences were linguistically simpler and demanded less processing compared to the sentences used in the RS test
Variability in verbal working memory was observed when participants were tested with the auditory WARRM test than with the visual RS test, most likely because the WARRM test was more sensitivity to individual differences in auditory processing

Summary

Introduction

For over a half century, researchers and clinicians have recognized that speech understanding difficulties are common amongst older listeners, when speech is presented in a noisy background or when listeners have age-related hearing loss (e.g., Bocca and Calearo, 1963; Frisina and Frisina, 1997; Gates and Mills, 2005; Mills et al, 2006; Humes and Dubno, 2010). Research examining the interactions between sensory and cognitive processes has resulted in the emerging field of cognitive hearing science, with much of the recent work in this field focusing on the role that working memory plays in speech understanding in listeners who may have various degrees and types of hearing loss (Arlinger et al, 2009). When the audibility of the speech signal is reduced due to hearing loss or noise, more working memory resources may need to be allocated when listeners are trying to comprehend the impoverished incoming speech signal (see Rabbitt, 1968, 1991; van Rooij and Plomp, 1990; Wingfield, 1996; Lunner, 2003; Humes and Floyd, 2005; Foo et al, 2007; Rudner et al, 2007, 2011; Akeroyd, 2008; Parbery-Clark et al, 2009; Besser et al, 2013). Some studies have been more successful than others in associating working memory and speech-recognition measures, perhaps in part due to the variations in the working memory and speech measures used

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