Categorical Perception of Pitch Contours and Voice Onset Time in Mandarin-Speaking Adolescents With Autism Spectrum Disorders

Categorical perception of lexical tones in Chinese people with post-stroke aphasia

This study used the categorical perception (CP) paradigm, a fine-grained perceptual method, to investigate the perceptual performance of lexical tones in Chinese people with post-stroke aphasia (PWA). Twenty patients with post-stroke aphasia (10 Broca's and 10 Wernicke's) and ten neurologically intact age-matched control participants were recruited to complete both identification and discrimination tasks of the Mandarin Tone 1-2 continuum. In addition, all participants completed tests on their auditory comprehension ability and working memory. The results showed that both Broca's and Wernicke's patients exhibited reduced sensitivity to within-category and between-category information but preserved CP of lexical tones. The degree of CP of lexical tones related to working memory in aphasic patients. Furthermore, lower-level acoustic processing underpinned higher-level phonological processing on the CP of lexical tones since both patient groups' unbalanced pitch processing ability extended to their CP of lexical tones. These findings are significant for researchers and clinicians in speech-language rehabilitation, clinical psychology, and cognitive communication.

Development of Mandarin Lexical Tone Identification in Noise and Its Relation With Working Memory

PURPOSE

This study aimed to examine the developmental trajectory of Mandarin tone identification in quiet and two noisy conditions: speech-shaped noise (SSN) and multitalker babble noise. In addition, we evaluated the relationship between tonal identification development and working memory capacity.

METHOD

Ninety-three typically developing children aged 5-8 years and 23 young adults completed categorical identification of two tonal continua (Tone 1-4 and Tone 2-3) in quiet, SSN, and babble noise. Their working memory was additionally measured using auditory digit span tests. Correlation analyses between digit span scores and boundary widths were performed.

RESULTS

Six-year-old children have achieved the adultlike ability of categorical identification of Tone 1-4 continuum under both types of noise. Moreover, 6-year-old children could identify Tone 2-3 continuum as well as adults in SSN. Nonetheless, the child participants, even 8-year-olds, performed worse when tokens from Tone 2-3 continuum were masked by babble noise. Greater working memory capacity was associated with better tone identification in noise for preschoolers aged 5-6 years; however, for school-age children aged 7-8 years, such correlation only existed in Tone 2-3 continuum in SSN.

CONCLUSIONS

Lexical tone perception might take a prolonged time to achieve adultlike competence in babble noise relative to SSN. Moreover, a significant interaction between masking type and stimulus difficulty was found, as indicated by Tone 2-3 being more susceptible to interference from babble noise than Tone 1-4. Furthermore, correlations between working memory capacity and tone perception in noise varied with developmental stage, stimulus difficulty, and masking type.

Sustainable Benefits of High Variability Phonetic Training in Mandarin-speaking Kindergarteners With Cochlear Implants: Evidence From Categorical Perception of Lexical Tones

OBJECTIVES

Although pitch reception poses a great challenge for individuals with cochlear implants (CIs), formal auditory training (e.g., high variability phonetic training [HVPT]) has been shown to provide direct benefits in pitch-related perceptual performances such as lexical tone recognition for CI users. As lexical tones in spoken language are expressed with a multitude of distinct spectral, temporal, and intensity cues, it is important to determine the sources of training benefits for CI users. The purpose of the present study was to conduct a rigorous fine-scale evaluation with the categorical perception (CP) paradigm to control the acoustic parameters and test the efficacy and sustainability of HVPT for Mandarin-speaking pediatric CI recipients. The main hypothesis was that HVPT-induced perceptual learning would greatly enhance CI users' ability to extract the primary pitch contours from spoken words for lexical tone identification and discrimination. Furthermore, individual differences in immediate and long-term gains from training would likely be attributable to baseline performance and duration of CI use.

DESIGN

Twenty-eight prelingually deaf Mandarin-speaking kindergarteners with CIs were tested. Half of them received five sessions of HVPT within a period of 3 weeks. The other half served as control who did not receive the formal training. Two classical CP tasks on a tonal continuum from Mandarin tone 1 (high-flat in pitch) to tone 2 (mid-rising in pitch) with fixed acoustic features of duration and intensity were administered before (pretest), immediately after (posttest), and 10 weeks posttraining termination (follow-up test). Participants were instructed to either label a speech stimulus along the continuum (i.e., identification task) or determine whether a pair of stimuli separated by zero or two steps from the continuum was the same or different (i.e., discrimination task). Identification function measures (i.e., boundary position and boundary width) and discrimination function scores (i.e., between-category score, within-category score, and peakedness score) were assessed for each child participant across the three test sessions.

RESULTS

Linear mixed-effects (LME) models showed significant training-induced enhancement in lexical tone categorization with significantly narrower boundary width and better between-category discrimination in the immediate posttest over pretest for the trainees. Furthermore, training-induced gains were reliably retained in the follow-up test 10 weeks after training. By contrast, no significant changes were found in the control group across sessions. Regression analysis confirmed that baseline performance (i.e., boundary width in the pretest session) and duration of CI use were significant predictors for the magnitude of training-induced benefits.

CONCLUSIONS

The stringent CP tests with synthesized stimuli that excluded acoustic cues other than the pitch contour and were never used in training showed strong evidence for the efficacy of HVPT in yielding immediate and sustained improvement in lexical tone categorization for Mandarin-speaking children with CIs. The training results and individual differences have remarkable implications for developing personalized computer-based short-term HVPT protocols that may have sustainable long-term benefits for aural rehabilitation in this clinical population.

Categorical perception of Mandarin lexical tones in language-delayed autistic children

Enhanced pitch perception has been identified in autistic individuals, but it remains understudied whether such enhancement can be observed in the lexical tone perception of language-delayed autistic children. This study examined the categorical perception of Mandarin lexical tones in 23 language-delayed autistic children and two groups of non-autistic children, with one matched on chronological age ( n = 23) and the other on developmental age in language ability ( n = 23). The participants were required to identify and discriminate lexical tones. A wider identification boundary width and a lower between-category discrimination accuracy were found in autistic children than their chronological-age-matched non-autistic peers, but the autistic group exhibited seemingly comparable performance to the group of developmental-age-matched non-autistic children. While both non-autistic groups displayed a typical categorical perception pattern with enhanced sensitivity to between-category tone pairs relative to within-category ones, such a categorical perception pattern was not observed in the autistic group. These findings suggest among language-delayed autistic children with a developmental age around 4, categorical perception is still developing. Finally, we found categorical perception performance correlated with language ability, indicating autistic children’s language disability might be predictive of their poor categorical perception of speech sounds.

Lay abstract

Some theories suggested that autistic people have better pitch perception skills than non-autistic people. However, in a context where pitch patterns are used to differentiate word meanings (i.e. lexical tones), autistic people may encounter difficulties, especially those with less language experience. We tested this by asking language-delayed autistic children to identify and discriminate two Mandarin lexical tones (/yi/ with Tone 1, meaning ‘clothes’; /yi/ with Tone 2, meaning ‘aunt’; /yi/: the standard romanization of Mandarin Chinese). On average, these autistic children were 7.35 years old, but their developmental age in language ability was 4.20, lagging behind 7-year-old non-autistic children in terms of language ability. Autistic children’s performance in identifying and discriminating lexical tones was compared with two groups of non-autistic children: one group was matched with the autistic group on age, and the other was matched based on language ability. Autistic children performed differently from the non-autistic children matched on age, while autistic and non-autistic children matched on language ability exhibited seemingly similar performance. However, both the non-autistic groups have developed the perceptual ability to process lexical tones as different categories, but this ability was still developing in autistic children. Finally, we found autistic children who performed worse in identifying lexical tones had poorer language ability. The results suggest that language disability might have adverse influence on the development of skills of speech sound processing.