L'effort associé à la reconnaissance de la parole chez les adultes et les personnes aînées
The primary objective of the current thesis was to quantify and compare the amount of listening effort that young and older, normal-hearing adults with normal (or corrected normal) vision expend when speech is presented in background noise.  Listening effort refers to the attentional and cognitive resources required to understand speech.  Study 1 was designed to determine the listening effort associated with auditory speech recognition (hearing a speaker) whereas Study 2 examined the listening effort involved with audiovisual speech recognition (hearing and seeing the face of a speaker).  Listening effort was assessed behaviourally, using a dual task paradigm where a word recognition task was paired with a tactile pattern recognition task and, with self-reported ratings.  Both measures of listening effort were assessed under two experimental conditions:  1) equated level - where the level of background noise was the same for all participants and, 2) equated performance - where single task word recognition performance did not differ between groups.  The tactile task costs revealed that older adults expended more listening effort than young adults for both experimental conditions regardless of the perceptual modality in which the speech stimuli were presented (i.e., audio-only and audiovisual).  Overall, the cost involved with tactile task performance was highest for older adults when speech was presented audiovisually. While visual cues can improve audiovisual speech recognition our results suggest they can also place an extra demand on processing resources with performance consequences for the word and tactile tasks under dual task conditions.  Consistent with the literature, the correlation findings of Study 1 and Study 2 support the idea that dual task measures and self-reported ratings each assess different aspects of listening effort.  As listening effort draws upon auditory and cognitive factors, the purpose of Study 3 was to determine to what extent the separate components of auditory working memory (capacity and processing) contribute towards the variance observed in listening effort and to determine if the pattern of working memory predictor variables changes with age.  Results of a sequential regression analysis for young adults indicated that a measure of auditory capacity (span size) was related to listening effort whereas a measure of auditory processing (alphabetical recall) was related to the cost associated with word recognition accuracy performance under dual task conditions.  However, these relationships did not extend to older adults or to the data obtained when the speech recognition tasks were performed audiovisually.  Further research is required to determine what cognitive factors underlie listening effort – especially for older adults.
Cognition Listening effort Dual task paradigm Aging Cognition Speech recognition Audiovisual speech recognition Working memory