Joan K.-Y. Ma

Effect of intonation on Cantonese lexical tones

In tonal languages, there are potential conflicts between the FO-based changes due to the coexistence of intonation and lexical tones. In the present study, the interaction of tone and intonation in Cantonese was examined using acoustic and perceptual analyses. The acoustic patterns of tones at the initial, medial, and final positions of questions and statements were measured. Results showed that intonation affects both the FO level and contour, while the duration of the six tones varied as a function of positions within intonation contexts. All six tones at the final position of questions showed rising FO contour, regardless of their canonical form. Listeners were overall more accurate in the identification of tones presented within the original carrier than of the same tones in isolation. However, a large proportion of tones 33, 21, 23, and 22 at the final position of questions were misperceived as tone 25 both within the original carrier and as isolated words. These results suggest that although the intonation context provided cues for correct tone identification, the intonation-induced changes in FO contour cannot always be perceptually compensated for, resulting in some erroneous perception of the identity of Cantonese tone.

Perceptual characteristics of Cantonese hypokinetic dysarthria

The aims of this study were to provide a perceptual speech ‘profile’ for Cantonese speakers with hypokinetic dysarthria, to examine the reliability of non‐expert listeners in perceptual judgements of dysarthric speech, and to investigate cross‐language differences in profiles of hypokinetic dysarthria. Participants included 19 speakers with Parkinsons disease and 10 speech‐language pathologists who served as listeners. Listeners rated 21 speech dimensions, using seven‐point interval scales. Mean intralistener agreement was 94.52% and mean interlistener reliability was 0.88 (Cronbachs alpha). Mean scale values (MSV) for each dimension ranged from 3.37 to 1.36. The perceptual profile of Cantonese hypokinetic dysarthria was largely similar to profiles for English and Japanese speakers; notable differences are discussed. Possible reasons for the relatively high reliability obtained are presented.

Dysprosody and Stimulus Effects in Cantonese Speakers with Parkinson's Disease.

BACKGROUND Dysprosody is a common feature in speakers with hypokinetic dysarthria. However, speech prosody varies across different types of speech materials. This raises the question of what is the most appropriate speech material for the evaluation of dysprosody. AIMS To characterize the prosodic impairment in Cantonese speakers with hypokinetic dysarthria associated with Parkinsons disease, and to determine the effect of different types of speech stimuli on the perceptual rating of prosody. METHODS & PROCEDURES Speech data in the form of sentence reading, passage reading, and monologue were collected from ten Cantonese speakers with Parkinsons disease. Perceptual analysis was conducted on ten prosodic parameters to evaluate five dimensions of prosody, based on a theoretical framework: pitch, loudness, duration, voice quality, and degree of reduction. OUTCOMES & RESULTS The results showed that the most severely affected prosodic parameters were monopitch, harsh voice, and monoloudness, followed by breathy voice and prolonged interval. Differences were noted between speakers with mild and moderate dysprosody. No statistically significant differences were found between the three types of stimuli. However, qualitative analysis revealed noticeable differences between the three stimuli in two speakers. CONCLUSIONS & IMPLICATIONS The prosodic profile of Cantonese speakers with hypokinetic dysarthria is similar to those of other languages (for example, English). The involvement of two new dimensions in the definition of prosody (voice quality and degree of reduction) provides additional insight in differentiating patients with mild and moderate dysarthria. Further investigation on the use of speech materials in the clinical evaluation of speech prosody in speakers with dysarthria is needed, as no single task was found to represent a patients performance under all circumstances.

Speech Prosody Across Stimulus Types for Individuals with Parkinson’s Disease

BACKGROUND Up to 89% of the individuals with Parkinsons disease (PD) experience speech problem over the course of the disease. Speech prosody and intelligibility are two of the most affected areas in hypokinetic dysarthria. However, assessment of these areas could potentially be problematic as speech prosody and intelligibility could be affected by the type of speech materials employed. OBJECTIVE To comparatively explore the effects of different types of speech stimulus on speech prosody and intelligibility in PD speakers. METHODS Speech prosody and intelligibility of two groups of individuals with varying degree of dysarthria resulting from PD was compared to that of a group of control speakers using sentence reading, passage reading and monologue. Acoustic analysis including measures on fundamental frequency (F0), intensity and speech rate was used to form a prosodic profile for each individual. Speech intelligibility was measured for the speakers with dysarthria using direct magnitude estimation. RESULTS Difference in F0 variability between the speakers with dysarthria and control speakers was only observed in sentence reading task. Difference in the average intensity level was observed for speakers with mild dysarthria to that of the control speakers. Additionally, there were stimulus effect on both intelligibility and prosodic profile. CONCLUSIONS The prosodic profile of PD speakers was different from that of the control speakers in the more structured task, and lower intelligibility was found in less structured task. This highlighted the value of both structured and natural stimulus to evaluate speech production in PD speakers.