Congruent Prosody Reduces Cognitive Effort in Memory for Spoken Sentences: A Pupillometric Study with Young and Older Adults.

BACKGROUND: In spite of declines in working memory and other processes, older adults generally maintain good ability to understand and remember spoken sentences. In part this is due to preserved knowledge of linguistic rules and their implementation. Largely overlooked, however, is the support older adults may gain from the presence of sentence prosody (pitch contour, lexical stress, intra-and inter-word timing) as an aid to detecting the structure of a heard sentence. METHODS: Twenty-four young and 24 older adults recalled recorded sentences in which the sentence prosody corresponded to the clausal structure of the sentence, when the prosody was in conflict with this structure, or when there was reduced prosody uninformative with regard to the clausal structure. Pupil size was concurrently recorded as a measure of processing effort. RESULTS: Both young and older adults' recall accuracy was superior for sentences heard with supportive prosody than for sentences with uninformative prosody or for sentences in which the prosodic marking and causal structure were in conflict. The measurement of pupil dilation suggested that the task was generally more effortful for the older adults, but with both groups showing a similar pattern of effort-reducing effects of supportive prosody. CONCLUSIONS: Results demonstrate the influence of prosody on young and older adults' ability to recall accurately multi-clause sentences, and the significant role effective prosody may play in preserving processing effort.

Strategic Pauses Relieve Listeners from the Effort of Listening to Fast Speech: Data Limited and Resource Limited Processes in Narrative Recall by Adult Users of Cochlear Implants.

Speech that has been artificially accelerated through time compression produces a notable deficit in recall of the speech content. This is especially so for adults with cochlear implants (CI). At the perceptual level, this deficit may be due to the sharply degraded CI signal, combined with the reduced richness of compressed speech. At the cognitive level, the rapidity of time-compressed speech can deprive the listener of the ordinarily available processing time present when speech is delivered at a normal speech rate. Two experiments are reported. Experiment 1 was conducted with 27 normal-hearing young adults as a proof-of-concept demonstration that restoring lost processing time by inserting silent pauses at linguistically salient points within a time-compressed narrative ("time-restoration") returns recall accuracy to a level approximating that for a normal speech rate. Noise vocoder conditions with 10 and 6 channels reduced the effectiveness of time-restoration. Pupil dilation indicated that additional effort was expended by participants while attempting to process the time-compressed narratives, with the effortful demand on resources reduced with time restoration. In Experiment 2, 15 adult CI users tested with the same (unvocoded) materials showed a similar pattern of behavioral and pupillary responses, but with the notable exception that meaningful recovery of recall accuracy with time-restoration was limited to a subgroup of CI users identified by better working memory spans, and better word and sentence recognition scores. Results are discussed in terms of sensory-cognitive interactions in data-limited and resource-limited processes among adult users of cochlear implants.

Adults with cochlear implants can use prosody to determine the clausal structure of spoken sentences.

Speech prosody, including pitch contour, word stress, pauses, and vowel lengthening, can aid the detection of the clausal structure of a multi-clause sentence and this, in turn, can help listeners determine the meaning. However, for cochlear implant (CI) users, the reduced acoustic richness of the signal raises the question of whether CI users may have difficulty using sentence prosody to detect syntactic clause boundaries within sentences or whether this ability is rescued by the redundancy of the prosodic features that normally co-occur at clause boundaries. Twenty-two CI users, ranging in age from 19 to 77 years old, recalled three types of sentences: sentences in which the prosodic pattern was appropriate to the location of a clause boundary within the sentence (congruent prosody), sentences with reduced prosodic information, or sentences in which the location of the clause boundary and the prosodic marking of a clause boundary were placed in conflict. The results showed the presence of congruent prosody to be associated with superior sentence recall and a reduced processing effort as indexed by the pupil dilation. The individual differences in a standard test of word recognition (consonant-nucleus-consonant score) were related to the recall accuracy as well as the processing effort. The outcomes are discussed in terms of the redundancy of the prosodic features, which normally accompany a clause boundary and processing effort.