Abstract
Listening to speech in noise depletes cognitive resources, affecting speech processing. The present study investigated how remaining resources or cognitive spare capacity (CSC) can be deployed by young adults with normal hearing. We administered a test of CSC (CSCT; Mishra et al., 2013) along with a battery of established cognitive tests to 20 participants with normal hearing. In the CSCT, lists of two-digit numbers were presented with and without visual cues in quiet, as well as in steady-state and speech-like noise at a high intelligibility level. In low load conditions, two numbers were recalled according to instructions inducing executive processing (updating, inhibition) and in high load conditions the participants were additionally instructed to recall one extra number, which was the always the first item in the list. In line with previous findings, results showed that CSC was sensitive to memory load and executive function but generally not related to working memory capacity (WMC). Furthermore, CSCT scores in quiet were lowered by visual cues, probably due to distraction. In steady-state noise, the presence of visual cues improved CSCT scores, probably by enabling better encoding. Contrary to our expectation, CSCT performance was disrupted more in steady-state than speech-like noise, although only without visual cues, possibly because selective attention could be used to ignore the speech-like background and provide an enriched representation of target items in working memory similar to that obtained in quiet. This interpretation is supported by a consistent association between CSCT scores and updating skills.
Highlights
Listening in noise challenges explicit cognitive abilities (Rönnberg et al, 2008, 2013)
In a recent publication (Mishra et al, 2013), we evaluated a test of cognitive spare capacity (CSC) (CSCT) that probes the ability to perform different executive tasks under high and low memory load based on two-digit numbers presented in the auditory modality, with or without a video of the talker’s face
The results of the present study replicate the results of Mishra et al (2013) by showing that CSC in young adults with normal hearing thresholds is sensitive to storage load and executive function but not generally related to working memory capacity (WMC) and that availability of visual cues may hinder executive processing of speech heard in quiet
Summary
Listening in noise challenges explicit cognitive abilities (Rönnberg et al, 2008, 2013). A substantial body of work has shown that once audibility has been accounted for, individual working memory capacity (WMC) accounts for a large part of the variance in the ability to understand speech in noise (Humes, 2007; Akeroyd, 2008) This is not surprising as speech understanding requires encoding of the speech input for temporary storage, inferring meaning and at the same preparing for an appropriate response (Pichora-Fuller and Singh, 2006; Rudner and Lunner, 2013). Because WMC is limited, fewer cognitive resources will remain after processing of a message heard in noise compared to one heard in quiet (Pichora-Fuller, 2007; Lunner et al, 2009) This line of argument has sparked recent interest in measuring cognitive spare capacity (CSC), that is, the cognitive capacity that remains once successful listening has taken place (Rudner et al, 2011a). It is likely to assist in appropriate fitting of hearing aids (Rudner et al, 2011a; Mishra et al, 2013)
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