Aging affects Mandarin speakers' understanding of focus sentences in quiet and noisy environments

Older adults experiencing normal aging make up most patients seeking services at audiology clinics. While research acknowledges that the speech perception abilities of aging adults can be diminished in lower-level speech identification or discrimination, there is less concern about how aging affects higher-level speech understanding, particularly in tonal languages. This study aimed to explore the effects of aging on the comprehension of implied intentions conveyed through prosodic features in Mandarin focus sentences, both in quiet and noisy environments.

Twenty-seven younger listeners (aged 17 to 26) and 27 older listeners (aged 58 to 77) participated in a focus comprehension task. Their task was to interpret SAVO (subject-adverbial-verb-object) sentences with five focus conditions (initial subject-focus, medial adverbial-focus, medial verb-focus, final object-focus, and neutral non-focus) across five background conditions: quiet, white noise (at 0 and -10-dB signal-to-noise ratios, SNRs), and competing speech (at 0 and -10-dB SNRs). Comprehension performances were analyzed based on accuracy rates, and underlying processing patterns were evaluated using confusion matrices.

Younger listeners consistently excelled across focus conditions in quiet settings, but their scores declined in white noise at the SNR of -10-dB. Older adults exhibited variability in scores across focus conditions but not in background conditions. They scored lower than their younger counterparts, with the highest scores observed in the comprehension of sentences featuring a medial adverbial-focus. Analysis of confusion matrices revealed that younger adults seldom mistook focus conditions, whereas older adults tended to comprehend the other focused items as medial adverbials.

Older listeners' performance reflects their over-reliance on top-down language knowledge, while their bottom-up acoustic processing decreases when interpreting Mandarin focus sentences. These findings provide evidence of active cognitive processing in prosody comprehension among aging adults and offer insights for diagnosing and intervening with speech disorders in clinical settings.