On The (Un)importance of Working Memory in Speech-in-Noise Processing for Listeners with Normal Hearing Thresholds.

Christian Füllgrabe,Stuart Rosen

doi:10.3389/fpsyg.2016.01268

Abstract

With the advent of cognitive hearing science, increased attention has been given to individual differences in cognitive functioning and their explanatory power in accounting for inter-listener variability in the processing of speech in noise (SiN). The psychological construct that has received much interest in recent years is working memory. Empirical evidence indeed confirms the association between WM capacity (WMC) and SiN identification in older hearing-impaired listeners. However, some theoretical models propose that variations in WMC are an important predictor for variations in speech processing abilities in adverse perceptual conditions for all listeners, and this notion has become widely accepted within the field. To assess whether WMC also plays a role when listeners without hearing loss process speech in adverse listening conditions, we surveyed published and unpublished studies in which the Reading-Span test (a widely used measure of WMC) was administered in conjunction with a measure of SiN identification, using sentence material routinely used in audiological and hearing research. A meta-analysis revealed that, for young listeners with audiometrically normal hearing, individual variations in WMC are estimated to account for, on average, less than 2% of the variance in SiN identification scores. This result cautions against the (intuitively appealing) assumption that individual variations in WMC are predictive of SiN identification independently of the age and hearing status of the listener.

Highlights

Over the past decades, there has been growing interest in the role of individual differences in cognitive functioning in speech processing, reflected by a noticeable increase in the number of scientific publications on this topic
Different definitions have been given for this theoretical construct but it is generally agreed that the capacity of the working memory (WM) system (WMC) can be reliably assessed by so-called complex span tasks
It could be argued that the cognitive and speech tests used in the studies surveyed here are suboptimal or inappropriate measures of WM capacity (WMC) and speech in noise (SiN) processing, respectively (e.g., Besser et al, 2012; Sörqvist and Rönnberg, 2012; Keidser et al, 2015)

Summary

Introduction

There has been growing interest in the role of individual differences in cognitive functioning in speech processing, reflected by a noticeable increase in the number of scientific publications on this topic (see Figure 1). A series of audiological research studies investigated whether individual differences in WMC, measured by the version of the RSpan test developed by Rönnberg et al (1989), can help predict unaided (Lunner, 2003; Rudner et al, 2011) and aided (Lunner, 2003; Foo et al, 2007; Rudner et al, 2008, 2009, 2011) speech perception in hearing-impaired (HI) listeners, and explain the user-dependent success of different types of signal-processing performed by the hearing aid (e.g., dynamic range or frequency compression; Souza et al, 2015).

Results

Conclusion