1. RESULTS AND DISCUSSION Fall Level High-rising Fall Level High-rising
Production of Tonal Contrasts in Punjabi by Brain Damaged Subjects
Chinar Dara & Marc D. Pell
School of Communication Sciences and Disorders, McGill University, Montréal, Canada
INTRODUCTION
METHODOLOGY
RESULTS AND DISCUSSION
Participants
4 unilateral left hemisphere damaged (LHD), 4 unilateral right hemisphere damaged (RHD), and 4 normal controls (NC).
native speakers of Punjabi
right-handed
with a minimum fourth grade education
normal hearing
scores on Diagnostic Test Battery for Aphasia in Hindi ranged from ‘minimal aphasia’ to ‘unassisted communication’
Table 1. Normalized f0 measures of onset and contour for all three Punjabi tones for all the subjects
Onset
Contour
Subject
Group
Fall Level High-rising
Fall Level High-rising 1M
LHD
0.99
1.03
-0.07
0.04 2M 1
-0.04
-0.02 3F
1.04
-0.01
0.05 4M
1.01
1.02
-0.06
0.02 5M
RHD
0.98
-0.09
0.07 6M
0.97
0.96
-0.03 7F
0.64
0.1 8F
-0.08
0.09 9M NC
0.95
10F
0.08
11F
12M
1.05
0.01
Prosody is a suprasegmental feature which can have linguistic and affective semantic manifestations.
Prosody has been studied considerably to elucidate the role of left and right hemispheres in the processing of linguistic tone and emotional tone (e.g. Baum & Pell, 1997; Van Lancker & Sidtis, 1992; Cancelliere & Kertesz, 1990)
Studies have shown a left hemisphere dominance for the processing of linguistic tones and more specifically lexical tones in a tone language. However, the pattern of deviances in tone production has been inconsistent (e.g. Thai, Mandarin) (Packard, 1986; Gandour, Ponglorpisit & Dardarananda, 19992).
In a tone language, tone is a part of its phonemic structure, thus every syllable or word may have a distinctive pitch pattern. Fundamental frequency (fo) is the critical acoustic cue in lexical tones.
Punjabi has three contrastive tones at the lexical level (Joshi, 1988, Narang, 1989) :
Falling – the pitch falls gradually
Level – the pitch shows minimal variation
High-rising – the pitch starts at a higher level and goes up further.
Patient No.
Age
Sex
Familial History
Months Post-Onset
Hemisphere of lesion
Anatomical location 1
70 yrs
Male No
2 mths
Left
Anterior- Cerebral Artery; Frontal 2
75 yrs
5 mths
Temporo – Parietal Region 3
60 yrs
Female
14 mths
Sub – Cortical Area; Frontal 4
25 yrs
MCA Infarct;
Fronto - Parietal 5
65 yrs
15 days
Right
Parietal Occipital 6
19 yrs
Yes (grand-mother)
1 mth
10 days
Basal Ganglionic;
Frontal Parietal 7
40 yrs
6 mths
Posterior Cerebral Artery; Temporal 8
32 yrs
8 mths
Frontal Temporal Parietal
Fig. 1. The variations in high-rising contour across the three groups.
Task
A picture naming task and a repetition task were constructed to elicit words containing one of the three Punjabi tones: Falling, Level, High-rising.
Picture Naming Task – Subjects were required to produce the word that the picture was referring to, which could be common objects, actions, colors or numbers.
Eg. /kòɽa/ “horse”
Repetition Task – 5 minimal pairs of words differing only in tones were used to construct ten different sentences. Subjects were required to repeat the complete utterance.
Eg. /us k ri ich pani-e / “That pitcher has water.”
/ɔ chaval nal k ri kha riya-e / “He is having curry with rice.”
For consistency in results fo was extracted at the onset, medial, and offset of four vowel sounds /ə/, /o/, /a/, /i/ for each of the three tones. Contour of each tone was computed by obtaining the difference between the onset and offset measures.
Objective
To address the issue of functional lateralization of prosody the study investigates the nature of deficit in the production of the three lexical tones of Punjabi by left and right hemisphere brain-damaged participants.
Fundamental frequency (fo), the acoustic feature of the prosodic structures, which is critical in conveying linguistic meaning in Punjabi, was analyzed as a measure of onset and contour.
Prediction
Left hemisphere is associated with the production of linguistic prosody. Impairment to the left hemisphere will result in deviant tone productions.
The ability of the LHD subjects to produce the contour of the high-rising tone was significantly impaired (p=0.05) and they also show a trend of producing higher fo onset (p<0.06) for falling tone when compard to NC. Thus all three Punjabi tones do not seem to be vulnerable to the same extent. As level tone and falling tone are easier to produce (Ohala, 1978), they are least susceptible to disruptions.
REFERENCES