Cognitive load during speech perception in noise: the influence of age, XXXX , and cognition on the pupil response.

@entity1 @entity384 @entity393 @entity73
OBJECTIVES: The aim of the present study was to evaluate the influence of age, @entity393 , and cognitive ability on the cognitive processing load during listening to speech presented in noise. Cognitive load was assessed by means of pupillometry (i.e., examination of @entity384 ), supplemented with subjective ratings. DESIGN: Two groups of subjects participated: 38 middle-aged @entity1 (mean age = 55 yrs) with normal hearing and 36 middle-aged @entity1 (mean age = 61 yrs) with @entity393 . Using three Speech Reception Threshold (SRT) in stationary noise tests, we estimated the speech-to-noise ratios (SNRs) required for the correct repetition of 50%, 71%, or 84% of the sentences (SRT50%, SRT71%, and SRT84%, respectively). We examined the pupil response during listening: the peak amplitude, the peak latency, the mean dilation, and the pupil response duration. For each condition, @entity1 rated the experienced listening effort and estimated their performance level. @entity1 also performed the Text Reception Threshold (TRT) test, a test of processing speed, and a word vocabulary test. Data were compared with previously published data from young @entity1 with normal hearing. RESULTS: @entity393 was related to relatively poor SRTs, and higher speech intelligibility was associated with lower effort and higher performance ratings. For listeners with normal hearing, increasing age was associated with poorer TRTs and slower processing speed but with larger word vocabulary. A multivariate repeated-measures analysis of variance indicated main effects of group and SNR and an interaction effect between these factors on the pupil response. The peak latency was relatively short and the mean dilation was relatively small at low intelligibility levels for the middle-aged groups, whereas the reverse was observed for high intelligibility levels. The decrease in the pupil response as a function of increasing SNR was relatively small for the listeners with @entity393 . Spearman correlation coefficients indicated that the cognitive load was larger in listeners with better TRT performances as reflected by a longer peak latency (normal-hearing @entity1 , SRT50% condition) and a larger peak amplitude and longer response duration ( @entity393 @entity1 , SRT50% and SRT84% conditions). Also, a larger word vocabulary was related to longer response duration in the SRT84% condition for the @entity1 with normal hearing. CONCLUSIONS: The pupil response systematically increased with decreasing speech intelligibility. Ageing and @entity393 were related to less release from effort when increasing the intelligibility of speech in noise. In difficult listening conditions, these factors may induce @entity73 relatively early or they may be associated with relatively shallow speech processing. More research is needed to elucidate the underlying mechanisms explaining these results. Better TRTs and larger word vocabulary were related to higher mental processing load across speech intelligibility levels. This indicates that utilizing linguistic ability to improve speech perception is associated with increased listening load.
