The Role of Lexical Tone Information in the Recognition of Mandarin Sentences in Listeners With Hearing Aids

Relationship between self-reported hearing and vision problems, cognitive decline, depressive symptoms, and life satisfaction in older adults: a retrospective observational study

BACKGROUND

Sensory impairment in older adults is associated with cognitive decline, elevated depressive symptoms, and low levels of life satisfaction. However, these relationships are usually investigated separately and in pairs. This study examined these relationships comprehensively, for the first time.

METHODS

The analysis included 5,658 community-dwelling older adults from the China Health and Retirement Longitudinal Study (aged 50 to 108 years, 52.1% male) who completed the Jorm Informant Questionnaire Cognitive Decline in the Elderly and the Center for Epidemiological Studies-Depression-short form. A questionnaire was used to collect information on hearing, visual status, and life satisfaction. Structural equation modelling was used to examine the direct and indirect relationships between these variables.

RESULTS

Self-reported hearing and vision problems are directly associated with cognitive decline and elevated depressive symptoms. In addition, hearing and vision problems are indirectly related to cognitive decline through elevated depressive symptoms. Although hearing and vision problems had no direct effect on life satisfaction, they were indirectly associated with life satisfaction through cognitive decline and depressive symptoms.

CONCLUSIONS

This study provides the first epidemiological evidence of the comprehensive relationships between hearing and vision problems, cognitive decline, depressive symptoms, and life satisfaction. When older adults report hearing and/or vision problems, clinicians and caregivers should be aware of the concurrence of declined cognition, elevated depressive symptoms, and compensated life satisfaction. Future studies should examine the causal relationships and potential mechanisms of these relationships.

Is Cantonese lexical tone information important for sentence recognition accuracy in quiet and in noise?

In Chinese languages, tones are used to express the lexical meaning of words. It is therefore important to analyze the role of lexical tone in Chinese sentence recognition accuracy. There is a lack of research on the role of Cantonese lexical tones in sentence recognition accuracy. Therefore, this study examined the contribution of lexical tone information to Cantonese sentence recognition accuracy and its cognitive correlates in adults with normal hearing (NH). A text-to-speech synthesis engine was used to synthesize Cantonese daily-use sentences with each word carrying an original or a flat lexical tone, which were then presented to 97 participants in quiet, in speech-shaped noise (SSN), and in two-talker babble (TTB) noise conditions. Both target sentences and noises were presented at 65 dB binaurally via insert headphones. It was found that listeners with NH can almost perfectly recognize a daily-use Cantonese sentence with mismatched lexical tone information in quiet, while their sentence recognition decreases substantially in noise. The same finding was reported for Mandarin, which has a relatively simple tonal system, suggesting that the current results may be applicable to other tonal languages. In addition, working memory (WM) was significantly related to decline in sentence recognition score in the TTB but not in the SSN, when the lexical tones were mismatched. This finding can be explained using the Ease of Language Understanding model and suggests that those with higher WM are less likely to be affected by the degraded lexical information for perceiving daily-use sentences in the TTB.

Brain hemispheres with right temporal lobe damage swap dominance in early auditory processing of lexical tones

Labor division of the two brain hemispheres refers to the dominant processing of input information on one side of the brain. At an early stage, or a preattentive stage, the right brain hemisphere is shown to dominate the auditory processing of tones, including lexical tones. However, little is known about the influence of brain damage on the labor division of the brain hemispheres for the auditory processing of linguistic tones. Here, we demonstrate swapped dominance of brain hemispheres at the preattentive stage of auditory processing of Chinese lexical tones after a stroke in the right temporal lobe (RTL). In this study, we frequently presented lexical tones to a group of patients with a stroke in the RTL and infrequently varied the tones to create an auditory contrast. The contrast evoked a mismatch negativity response, which indexes auditory processing at the preattentive stage. In the participants with a stroke in the RTL, the mismatch negativity response was lateralized to the left side, in contrast to the right lateralization pattern in the control participants. The swapped dominance of brain hemispheres indicates that the RTL is a core area for early-stage auditory tonal processing. Our study indicates the necessity of rehabilitating tonal processing functions for tonal language speakers who suffer an RTL injury.

Speech Perception in Noise Is Associated With Different Cognitive Abilities in Chinese-Speaking Older Adults With and Without Hearing Aids

Chinese-speaking older adults usually do not perceive a hearing problem until audiometric thresholds exceed 45 dB HL, and the audiometric thresholds of the average hearing-aid (HA) user often exceed 60 dB HL. The purpose of this study was to examine the relationships between cognitive and hearing functions (measured as audiometric or speech reception thresholds) in older Chinese adults with HAs and with untreated hearing loss (HL). Participants were 49 Chinese older adults who used HAs and had moderate to severe HL (HA group), and 46 older Chinese who had mild to moderately severe HL but did not use HAs (untreated; or UT group). Multiple linear regression analysis was employed to evaluate how well age, education level, audiometric thresholds, and speech perception in noise were related to performance on general cognitive function, working memory, executive function, attention, and verbal learning tests. Results showed that speech perception in noise alone accounted for 13–25% of the variance in general cognitive function, working memory, and executive function in the UT group, and 9–21% of the variance in general cognitive function and verbal learning in the HA group (i.e., medium effect sizes). Audiometric thresholds did not explain any proportion of the variance in cognitive functioning in the HA or UT group. Thus, speech perception in noise accounts for more variance in cognitive performance than audiometric thresholds, and is significantly associated with different cognitive functions in older Chinese adults with HAs and with untreated HL.

Can Dual Compression Offer Better Mandarin Speech Intelligibility and Sound Quality Than Fast-Acting Compression?

The aim of this study was to evaluate the efficacy of dual compression for Mandarin-speaking hearing aid users. Dual compression combines fast and slow compressors operating simultaneously across all frequency channels. The study participants were 31 hearing aid users with symmetrical moderate-to-severe hearing loss, with a mean age of 67 years. A new pair of 20-channel behind-the-ear hearing aids (i.e., Phonak Bolero B90-P) was used during the testing. The results revealed a significant improvement in speech reception thresholds in noise when switching from fast-acting compression to dual compression. The sound quality ratings revealed that most listeners preferred dual compression to fast-acting compression for listening effort, listening comfort, speech clarity, and overall sound quality at +4 dB signal-to-noise ratio. These results are consistent with predictions based on the theoretical understanding of dual and fast-acting compression. However, whether these results can be generalized to other languages or other dual compression systems should be verified by future studies.