Department of Theoretical and Applied Linguistics, School of English Language and Literature, Aristotle University of Thessaloniki.



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Anna Sfakianaki

Thesis Outline:

Originally research in acoustic phonetics focused more on the static characteristics of segments of speech. But in the late 1960s the interest shifted towards the dynamics of speech and the rules governing the fusion of strings of phonemes into connected speech. The notion of coarticulation assumes that a sound is influenced by its neighbouring phonemes and this sort of influence is called coarticulation effect.

Coarticulation phenomena in the speech of the hearing-impaired have been the focus of considerable recent research. Deaf speakers tend to treat phonemes, syllables and words as isolated events rather than as integrated parts of an event of greater magnitude and their vowel formants tend to be ‘flat’ when compared to those of normal speakers. This has a negative effect on deaf speech intelligibility.

The present study will primarily attempt to investigate vowel-to-vowel carryover and anticipatory coarticulation effects in the speech of Greek adults with normal hearing and hearing impairment.

The hearing-impaired (HI) subjects are members of the Association of the Hard of Hearing of the county of Thessaloniki. Ten adults (balanced numbers for sex), 20-26 years old, with varying degrees of hearing impairment took part in the experiment. They can be categorised into two groups: Group A: subjects with a hearing loss of more than 100dB (profoundly deaf) and Group B: subjects with a hearing loss less than 100dB (75-99dB, severely deaf). Five adults with normal hearing (NH) constitute the control group. They were all born and raised in Thessaloniki, speak standard Greek with no detectable accent and are matched for sex and age with the hearing impaired subjects.

In order to investigate the relationship between coarticulation and speech intelligibility, an intelligibility test was set up. The HI subjects uttered 101 words and 25 sentences (8-14 syllables in total) which contain frequently used Greek clusters and all Greek phonemes in word-initial position at least once. An experiment with 30 naive listeners who judge the material is in progress. Finally an intelligibility score (1-5) will be given to each HI subject.

Concerning the acoustic analysis, the stimuli will be disyllabic nonsense words of the structure ‘pVCV’. The vowel will be /i/ /a/ or /u/ and the consonant will be /p/, /t/ or /s/. In this way we can examine the vowel-to-vowel effects in the context of consonants in two articulation places (bilabial and alveolar) and in two manners (stop and fricative). Stress will also vary its position. This renders 9 different stimuli for each consonant, so there will be 54 different stimuli in total. An example for ‘t’ is the following:

t ‘pata ‘pati ‘patu ‘piti ‘pita ‘pitu ‘putu
‘puta
 ‘puti
  pa’ta pa’ti pa’tu pi’ti pi’ta pi’tu pu’tu pu’ta pu’ti

The stimulus will be placed within the carrier phrase ‘ËÝãå _____ ðÜëé’ (Say ____ again’) and each sentence will be repeated 10 times. The 540 sentences will be randomised.

Praat (doing phonetics by computer, copyright ©1992-2004 by Paul Boersma and David Weenink) will be used for the acoustic analysis. F1 and F2 will be measured at the onset, midpoint and end of each vowel so as to monitor the formant movement throughout each disyllable. For the formant onset value, the cursor will be placed at the onset of the second cycle of clear complex periodic activity so as to get a reliable reading from a Gaussian window. The formant offset value will be measured at the end of the cycle with clear complex periodic activity. In addition duration will be measured for each vowel from a waveform display. The left and right cursors will be placed at the onset and offset of complex periodic activity respectively.

The measurements will be analysed statistically for each subject and for each group. The results will attempt to shed light on the coarticulation effects in respect to factors such as: a) the nature of the vowel, b) stress, c) consonant type (place and manner), d) sex (male or female), e) normal vs. impaired hearing, f) degree of hearing-impairment, g) intelligibility score.



Selected bibliography:

Baum, S. & Waldstein R. (1991). Perservatory coarticulation in the speech of profoundly hearing-impaired and normally-hearing children. J Speech Lang Hear Res. (vol. 34). 1286-1292.
 
Fowler, C. (1981). Production and perception of coarticulation among stressed and unstressed vowels. J. Speech & Hear Res. (vol. 24). 127-139.
 
Gay, T. (1977). Articulatory movements in VCV sequences. J Acoust Soc Am. (vol. 62). 183-193.
 
Monsen, R.B. (1974). Durational aspects of vowel production in the speech of deaf children. J. Speech Hear. Res. (vol. 17). 386-398.
 
Monsen, R.B. (1976). Second formant transitions of selected consonant-vowel combinations in the speech of deaf and normally-hearing children. J. Speech Hear. Res. (vol. 19). 279-289.
 
Nicolaidis, K. (1997) 'An electropalatographic study of Vowel-to-Consonant coarticulation in Greek'. Proceedings of the 10th International Symposium on Theoretical and Applied Linguistics, 24-26 April 1996, Thessaloniki, Greece, 105-115.
 
Nicolaidis, K. (1999) ‘The influence of stress on V-to-V coarticulation: an electropalatographic study’. Proceedings of the XIV International Congress of Phonetic Sciences, 1-7 August, San Fransisco, California, USA. pp. 1087-1090.
 
Nicolaidis, K. (2001) I efarmogi tis technikis tou electropalatografou logotherapeftiki paremvasi tou kofou/barikoou atomou (The use of the technique of electropalatography in speech therapy intervension for the hearing impaired). Proceedings of the 1st Colloquium on the Hearing Impaired: Communication, Technology, Education. September 2000, Aristotle University of Thessaloniki, 41-55.
 
Nicolaidis, K. (2002) Consonant lingual-palatal patterns produced by hearing-impaired speakers: two case studies. Proceedings of the 5th International Conference on Greek Linguistics, 13-16 September 2001, Paris, France.
 
Okalidou. A., Harris, K.S. (1999). A comparison of intergestural patterns in deaf and hearing adult speakers: implications from an acoustic analysis of disyllables. J Acoust Soc Am. (vol. 106). 394-410.
 
Okalidou, A. (2002). Barikoia-Kofosi –Meleti tis paragogis tou logou kai therapeutiki parembasi. (Hearing impaiment-Deafness –A study of speech production and speech therapy intrvension). Athens: Ellinika Grammata.
 
Rothman, H. (1976). A spectrographic investigation of consonant-vowel transitions in the speech of deaf adults. Journal of Phonetics. (vol. 4). 129-136.
 
Ryalls, J., Baum, S., Samuel, R., Larouche, A., Lacoursiere, N. & Garceau, J. (1993). Anticipatory co-articulation in the speech of young normal and hearing-impaired French Canadians. European Journal of Disorders of Communication. (vol. 28). 87-101.
 
Sereno, J. Baum, S., Marean, C. & Lieberman, P. (1987). Acoustic analyses and perceptual data on anticipatory labial coarticulation in adults and children. J. Acoust. Soc. Am. (vol. 81). 512-519.
 
Waldstein, R. & Baum, S. (1991). Anticipatory coarticulation in the speech of profoundly hearing-impaired and normally hearing children. J. Speech Lang. & Hear. Res. (vol. 34). 1276-1285.
 
Whitehead, R. & Jones, K. (1976). Influence of consonant environment on duration of vowels produced by normal-hearing, hearing-impaired and deaf adult speakers. J. Acoust. Soc. Am. (vol. 60). 513-515.
 
Whitehead, R. & Jones, K. (1978). The effect of vowel environment on duration of consonants produced by normal-hearing, hearing-impaired and deaf adult speakers. Journal of Phonetics. (vol. 6). 77-81.