Aging effect on Mandarin Chinese vowel and tone identification

Lexical tone perception and learning in older adults: A review and future directions

While the literature is well represented in accounting for how aging influences segmental properties of speech, less is known about its influences on suprasegmental properties such as lexical tones. In addition, foreign language learning is increasingly endorsed as being a potential intervention to boost cognitive reserve and overall well-being in older adults. Empirical studies on young learners learning lexical tones are aplenty in comparison with older learners. Challenges in this domain for older learners might be different due to aging and other learner-internal factors. This review consolidates behavioural and neuroscientific research related to lexical tone, speech perception, factors characterising learner groups, and other variables that would influence lexical tone perception and learning in older adults. Factors commonly identified to influence tone learning in younger adult populations, such as musical experience, language background, and motivation in learning a new language, are discussed in relation to older learner groups and recommendations to boost lexical tone learning in older age are provided based on existing studies.

Aging-Related Decline in Phonated and Whispered Speech Perception Not Compensated For by Increased Duration and Intensity: Evidence From Mandarin-Speaking Adult Listeners

PURPOSE

This study aimed to examine how aging and modifications of critical acoustic parameters may affect the perception of whispered speech as a degraded signal.

METHOD

Forty Mandarin-speaking adults were included in the study. Part 1 of the study compared the perception of Mandarin lexical tones, vowels, and syllables in older and younger adults in whispered versus phonated speech conditions. Parts 2 and 3 further examined how modification of duration and intensity cues contributed to the perceptual outcomes.

RESULTS

Perception of whispered tones was compromised in older and younger adults. Older adults identified lexical tones less accurately than their younger counterparts, particularly for phonated T2 and T3 and whispered T3. Aging also negatively affected the vowel identification of /i, u/ in the whispered condition. Syllable-level accuracy was largely dependent on the accuracy of lexical tones and vowels. Furthermore, reduced duration led to the decreased accuracy of phonated T3 and whispered T2 and T3 but increased accuracy of phonated T4. Reduced intensity lowered the recognition accuracy for phonated vowels /i, ɤ, o, y/ in older adults and /i, u/ in younger adults, and it also lowered the accuracy of whispered vowels /a, ɤ/ in older adults. Contrary to our expectation, increased duration and intensity did not improve older adults' speech perception in either phonated or whispered conditions.

CONCLUSIONS

The results suggest that aging adversely affected speech perception in both phonated and whispered conditions with more challenges in identifying whispered speech for older adults. While older adults' diminished performance may be potentially due to problems with processing the degraded temporal and spectral information of the target speech sounds, it cannot be simply compensated for by increasing the duration and intensity of the target sounds beyond the audible level.

Audiovisual Mandarin Lexical Tone Perception in Quiet and Noisy Contexts: The Influence of Visual Cues and Speech Rate

PURPOSE

Armed with the theory of embodied cognition proposing tight interactions between perception, motor, and cognition, this study aimed to test the hypothesis that speech rate-altered Mandarin lexical tone perception in quiet and noisy environments could be affected by the bodily dynamic cross-modal information.

METHOD

Fifty-three adult listeners completed a Mandarin tone perception task with 720 tone stimuli in auditory-only (AO), auditory-facial (AF), and auditory-facial-plus-gestural (AFG) modalities, at fast, normal, and slow speech rates under quiet and noisy conditions. In AF and AFG modalities, both congruent and incongruent audiovisual information were designed and presented. Generalized linear mixed-effects models were constructed to analyze the accuracy of tone perception across different conditions.

RESULTS

In Mandarin tone perception, the magnitude of enhancement of AF and AFG cues across three speech rates was significantly higher than that of the AO cue in the adverse context of noise, yet additional metaphoric gestures did not show significant differences from the facial information. Furthermore, the performance of auditory tone perception at the fast speech rate was significantly better than that at the normal speech rate when the inputs were incongruent between auditory and visual channels in quiet.

CONCLUSIONS

This study provided compelling evidence showing that integrated audiovisual information plays a vital role not only in improving lexical tone perception in noise but also in modulating the effects of speech rate on Mandarin tone perception in quiet for native listeners. Our findings, supporting the theory of embodied cognition, are implicational for speech and hearing rehabilitation among both young and old clinical populations.

The effect of aging on identification of Mandarin consonants in normal and whisper registers

Consonant perception in older adults has been widely explored in recent years. However, how aging affects the identification of Mandarin consonants, especially in whispered condition, are under studied. Mandarin consonants and whispering speech have unique features, which may result in different identification difficulties for older adults. The current study investigated older adults' identification of Mandarin consonants in phonated and whispered conditions in comparison with the performance of younger adults. It was found that in phonated condition, older adults showed the lowest accuracy for affricatives and fricatives owing to their insensitivity to high-frequency information. The lower accuracy of affricatives and plosives was largely attributed to the difficulty in recognizing articulatory places. Identifying aspirated plosives was much more difficult than unaspirated counterparts for older adults. In whispered condition, the recognition of voiced consonants and aspirated-unaspirated distinction became challenging, especially for older adults. Contrary to the expectation, some consonants became easier to be recognized in the whispered condition, i.e., /p^h, tɕ^h, x/. These findings enrich our understanding of how aging affects consonant identification in different languages and less ideal conditions. It also suggests that the listener's ability, language uniqueness, and characteristics of distorted speech should be all taken into consideration when investigating speech perception in adverse conditions.

Aging Effect on Mandarin Chinese Vowel and Tone Identification in Six-Talker Babble

Purpose The purpose of this study was to measure Mandarin Chinese vowel-plus-tone identification in quiet and noise for younger and older listeners. Method Two types of noise served as the masker, namely, six-talker babble and babble-modulated noise, at two signal-to-noise ratios (SNRs) of -4 and -8 dB. Fourteen listeners from both age groups were recruited, and three sets of data analyses were conducted: the identification of vowel plus tone, the identification of vowel, and the identification of tone. Results Younger listeners outperformed older listeners in all listening conditions, whereas the younger-older listener difference became greater in noise than in quiet, indicating a more detrimental effect of noise for older listeners than for younger listeners. In addition, vowel identification showed slightly better scores than tone identification in noise, suggesting that noise appeared to affect tone perception more negatively than vowel perception in Mandarin Chinese. At -4 dB SNR, there was a significantly greater amount of informational masking (IM) and a greater amount of energetic masking (EM) for older listeners than for younger listeners. At -8 dB SNR, there was a greater amount of EM for older listeners than for younger listeners but with no group difference in the amount of IM. Conclusion These results suggest that older listeners received a more negative impact of noise for Mandarin Chinese phonemic and tone recognition and had a larger amount of IM or EM from competing speech noise than younger listeners, depending on the SNR.

Aging Effects on Categorical Perception of Mandarin Lexical Tones in Noise

Purpose The purpose of this study was to examine the aging effects on the categorical perception (CP) of Mandarin lexical Tones 1-4 and Tones 1-2 in noise. It also investigated whether listeners' categorical tone perception in noise correlated with their general tone identification of 20 natural vowel-plus-tone signals in noise. Method Twelve younger and 12 older listeners with normal hearing were recruited in both tone identification and discrimination tasks in a CP paradigm where fundamental frequency contours of target stimuli varied systematically from the flat tone (Tone 1) to the rising/falling tones (Tones 2/4). Both tasks were conducted in quiet and noise with signal-to-noise ratios set at -5 and -10 dB, respectively, and general tone identification of natural speech signals was also tested in noise conditions. Results Compared with younger listeners, older listeners had shallower identification slopes and smaller discrimination peakedness in Tones 1-2/4 perception in all listening conditions, except for Tones 1-4 perception in quiet where no group differences were found. Meanwhile, noise affected Tones 1-2/4 perception: The signal-to-noise ratio condition at -10 dB brought shallower slope in Tones 1-2/4 identification and less peakedness in Tones 1-4 discrimination for both listener groups. Older listeners' CP in noise, the identification slopes in particular, positively correlated with their general tone identification in noise, but such correlations were partially missing for younger listeners. Conclusions Both aging and the presence of speech-shaped noise significantly reduced the CP of Mandarin Tones 1-2/4. Listeners' Mandarin tone recognition may be related to their CP of Mandarin tones.

Vowel and Tone Identification for Mandarin Congenital Amusics: Effects of Vowel Type and Semantic Content

Purpose This study aimed to explore the effects of Mandarin congenital amusia with or without lexical tone deficit (i.e., tone agnosia and pure amusia) on Mandarin vowel and tone identification in different types of vowels (e.g., monophthong, diphthongs, and triphthongs) embedded in consonant-vowel contexts with and without semantic content. Method Thirteen pure amusics (i.e., amusics with normal lexical processing), 5 tone agnosics (i.e., with lexical tone deficit), and 12 controls were screened with Montreal Battery of Evaluation of Amusia and lexical tone tests (Nan et al., 2010; Peretz et al., 2003). Vowel-plus-tone identification tasks with the factors of vowel type and syllables with and without semantic content (e.g., real and nonsense words) were examined among the 3 groups, and identification scores were calculated in 3 formats: vowel-plus-tone identification, vowel identification, and tone identification. Results Tone agnosics showed significantly poorer performances on identifications of vowel, tone, and vowel plus tone across monophthongs, diphthongs, and triphthongs in both real and nonsense words compared to pure amusics and controls. Their deficits were similar across the 3 types of vowels, while the deficit on vowel-plus-tone identification was more severe in nonsense words than in real words. On the other hand, pure amusics performed similarly with controls across all these conditions. Conclusions Tone agnosia might affect both musical pitch and phonological processing, resulting in deficits in lexical tone and vowel perception. On the contrary, pure amusics's effect is primarily on musical pitch perception but not on lexical tone or phonemic deficit. Vowel type did not affect speech deficits for tone agnosics, while they relied more on semantic content as a compensation.

Categorical Perception of Mandarin Chinese Tones 1-2 and Tones 1-4: Effects of Aging and Signal Duration

PURPOSE

The purpose of this study was to investigate the aging effect on the categorical perception of Mandarin Chinese tones with varied fundamental frequency (F0) contours and signal duration.

METHOD

Both younger and older native Chinese listeners with normal hearing were recruited in 2 experiments: tone identification and tone discrimination on a series of stimuli with the F0 contour systematically varying from the flat tone to the rising-falling tones. Apart from F0 contour, tone duration was manipulated at 3 levels: 100, 200, and 400 ms.

RESULTS

Results suggested that, compared with younger listeners, older listeners performed with shallower slope in the identification function and smaller peakedness in the discrimination function, particularly for Tones 1 and 2, whereas for Tones 1 and 4, comparable categorical perception was found between younger and older listeners.

CONCLUSIONS

The current study suggested that longer duration facilitated categorical perception in the flat-rising tones for the older listeners. Such an aging effect was not found with the flat-falling tones, suggesting that the aging-related deficit in categorical perception might relate to different tone types. Aging resulted in less categoricality of Mandarin tone perception for the flat-rising tones with short duration like 100 ms, possibly due to the aging-related decline in temporal processing.

Use of semantic context and F0 contours by older listeners during Mandarin speech recognition in quiet and single-talker interference conditions

This study followed up Wang, Shu, Zhang, Liu, and Zhang [(2013). J. Acoust. Soc. Am. 34(1), EL91-EL97] to investigate factors influencing older listeners' Mandarin speech recognition in quiet vs single-talker interference. Listening condition significantly interacted with F₀ contours but not with semantic context, revealing that natural F₀ contours provided benefit in the interference condition whereas semantic context contributed similarly to both conditions. Furthermore, the significant interaction between semantic context and F₀ contours demonstrated the importance of semantic context when F₀ was flattened. Together, findings from the two studies indicate that aging differentially affects tonal language speakers' dependence on F₀ contours and semantic context for speech perception in suboptimal conditions.

Aging Effect on Categorical Perception of Mandarin Tones 2 and 3 and Thresholds of Pitch Contour Discrimination

PURPOSE

The purpose of the study was to examine the aging effect on the categorical perception of Mandarin Chinese Tone 2 (rising F0 pitch contour) and Tone 3 (falling-then-rising F0 pitch contour) as well as on the thresholds of pitch contour discrimination.

METHOD

Three experiments of Mandarin tone perception were conducted for younger and older listeners with Mandarin Chinese as the native language. The first 2 experiments were in the categorical perception paradigm: tone identification and tone discrimination for a series of stimuli, the F0 contour of which systematically varied from Tone 2 to Tone 3. In the third experiment, the just-noticeable differences of pitch contour discrimination were measured for both groups.

RESULTS

In the measures of categorical perception, older listeners showed significantly shallower slopes in the tone identification function and significantly smaller peakedness in the tone discrimination function compared with younger listeners. Moreover, the thresholds of pitch contour discrimination were significantly higher for older listeners than for younger listeners.

CONCLUSION

These results suggest that aging reduced the categoricality of Mandarin tone perception and worsened the psychoacoustic capacity to discriminate pitch contour changes, thereby possibly leading to older listeners' difficulty in identifying Tones 2 and 3.