A preliminary acoustic experiment on tone production by a Cantonese post-stroke aphasic speaker

A standard paradigm for tone production studies is to ask informants to read a set of isolated syllables which are minimal pairs of tones, and these syllables are recorded and further analyzed. This paper reports a preliminary acoustic experiment on tone production by a Cantonese post-stroke aphasic patient, KF, who is a male speaker aged 52 and with lesion in left hemisphere. KF was asked to read aloud a list of syllables “夫 fu1, 苦 fu2, 富 fu3, 符 fu4, 婦 fu5, 父 fu6”, which are a set of minimal pairs of Cantonese six tones. KF was also asked to describe the family scene picture in Cantonese Aphasia Battery (E. M. Yiu, 1992). The sound recordings of these two tasks (isolated tones: 3 repetitions per tone; tones in speech: 6~11 items per tone) were analyzed and compared with those data of normal people (L. Zhang, 2017), as juxtaposed in Fig. 1. In isolated form, as shown in Fig. 1a and Fig. 1b, the aphasic patient exhibits a pattern of severely collapsed T3, T6, and T5; only the patterns of T1, T4 and T2 are comparable to normal people. Especially T5, which should be a rising tone, is mispronounced as a falling tone by KF. Thus, from the perspective of traditional tone research method (only to study isolated citation form), KF should be judged to have severe disruption in tone production. However, the tone patterns shown in Fig. 1c and Fig. 1d are very similar, which indicates that KF can produce the six tones correctly in continuous speech. This pilot study tells us that tone production in different contexts may lead to very different judgements and conclusions for aphasic patients. A more comprehensive study should be carried out to further assess the tone production problems of aphasic patients. Copyright © 2018 LSHK Annual Research Forum 2018.