Thesis (B.Sc)--University of Hong Kong, 2001. / "A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, May 4, 2001." Also available in print.

Thesis (B.Sc)--University of Hong Kong, 2001. / "A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, May 4, 2001." Also available in print.

Thesis (B.Sc)--University of Hong Kong, 2002. / "A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, May 10, 2002." Also available in print.

Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: Julie Sedivy. Includes bibliographical references (leaves 167-178). Also available online.

Thesis (Ph. D.)--Ohio State University, 1972. / Includes vita. Includes bibliographical references (leaves 72-75). Available online via OhioLINK's ETD Center.

Phonetic perception becomes native-like by 10 months of age. A potential mechanism of change, distributional learning, affects the perception of 6-8-month-old infants (Maye et al., 2002). However, it was anticipated that perception may be more difficult to change by 10 months of age, after native categories have developed. In fact, some evidence suggests that by this age, the presence of social interaction may be an important element in infants’ phonetic change (Kuhl et al., 2003). The current work advances the hypothesis that infants’ level of attention, which tends to be higher with social interaction, may be a salient factor facilitating phonetic change. Three experiments were designed to test infants’ phonetic plasticity at 10 months, after phonetic categories have formed. A non-social distributional learning paradigm was chosen, and infants’ attention was monitored to probe whether a facilitating role would be revealed. In Experiment 1, 10-month-old English-learning infants heard tokens from along a continuum that is no longer discriminated at this age that formed a distribution suggestive of a category boundary (useful distinction). The results failed to reveal evidence of discrimination, suggesting that the distributional information did not have any effect. A second experiment used slightly different sound tokens, ones that are farther from the typical English pronunciation and are heard less frequently in the language environment. Infants still failed to discriminate the sounds following the learning period. However, a median split revealed that the high attending infants evinced learning. Experiment 3 increased the length of the learning phase to allow all infants to become sufficiently high attending, and revealed phonetic change. Thus, after phonetic categories have formed, attention appears to be important in learning. / Arts, Faculty of / Psychology, Department of / Graduate

In the present study, dichotic listening performance of two-year-old children was investigated. Single pairs of words were presented dichoticaly to thirty-one children between GA 2-0-12 and 3-1-20. Each subject was asked to point to pictures of what he had heard. For each pair of words presented, a subject was shown three pictures, which corresponded to the two stimulus words and a foil word. Differences between number of correct responses for each ear were evaluated by means of a t test. Words presented to the right ear were more efficiently recalled than words presented to the left ear, in this age group , which suggests that the left hemisphere has achieved some degree of dominance for language by age two. No statisticaly significant differences were noted, in degree of right ear advantage, between males and females. When studies using school age and adult subjects are compared, it appears that the right ear advantage does not change in magnitude or direction from age two until adulthood. Results of the present investigation are discussed in relation to existing theories of the development of cerebral lateralization. An attempt was made to relate experimental results from dichotic listening,. EEG, and clinical studies. Limitations of the experiment, as wall as suggestions for further research, are discussed. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

Two hundred and eight Ss from grades 2, 4, and 6 were tested for recognition of dichotically presented musical stimuli, sound effects, and CVC nonsense syllables differing in medial vowel or initial stop consonant. Ear asymmetry was found to increase from grade 2 to grade 6. The left-ear advantage found for music, sound effects, and vowel-varied stimuli was due to decreasing right-ear performance with age. A right-ear advantage for consonants was the result of increasing right-ear performance and a simultaneous decrease in left-ear performance with age. These results were discussed in terms of a unilateral dominance specific for speech as opposed to a bilateral dominance for both speech and nonspeech material. Sex differences were found in the development of ear asymmetry, girls showing ear asymmetry earlier than boys in the recognition of verbal material and boys showing ear asymmetry earlier than girls in the recognition of sound effects. The results of the study were compared with those of a similar study using adults as Ss. The comparison showed that substantially larger ear asymmetries were obtained with grade 6 Ss than with adults. This difference was found to be due to the children's inferior recognition of stimuli presented to the nonpreferred ear, preferred ear performance being the same for both groups. The possibility of a covert order of report factor influencing the magnitude of the ear asymmetry found was suggested. / Arts, Faculty of / Psychology, Department of / Graduate

Previous research has revealed that very young infants discriminate most speech contrasts with which they are presented whether the contrasts are native or non-native while adults have difficulty discriminating non-native speech contrasts but easily discriminate those contrasts holding meaningful (phonemic) status in their native language. Several studies have shown that this reorganization in phonetic perception from language-general perception to language-specific perception occurs at about 10 to 12 months: infants this age attend only to native phonemic contrasts. It is of interest to determine if exposure to a phonetic variant plays an important role in influencing perception. We know from previous research that absence of exposure does not always lead to a lack of discrimination. This thesis was designed to determine if exposure per se maintains discriminability. To this end English-speaking adults and infants were tested using a phonetic distinction that does not hold phonemic status in English but does occur in English. This distinction involves the phonetic variants [da] and the stop produced following /s/ transcribed as [ta]. When tested in an identification procedure, English-speaking adults identify both [da] and (s)[ta] as members of one English phonemic category (i.e. [da]). When tested in a discrimination procedure and a category change procedure, adults discriminate (s) [ta] from [da] (albeit not as well as would be expected for a native phonemic contrast). With respect to infants, 6- to 8-month-olds discriminate this distinction revealing further support for broad-based phonetic perception at this age. However, 10- to 12-month-old infants do not discriminate, suggesting that the native phonemic status of the contrast (but not exposure) is the important factor in the reorganization. Discussion centers around how these results add to the existing literature and why infants of 10- to 12-months would fail to discriminate a native phonetic distinction. / Arts, Faculty of / Psychology, Department of / Graduate

This study investigates the relationship of articulatory variation to the visual perception of phonemes. Normal hearing and hearing-impaired subjects who had demonstrated good lipreading skills on a pilot test were selected to lipread videotaped tests under visual only conditions. Eighty-one V₁CV₂ utterances where V could be /I,æ,u/ and C could be /p,t,k, tϚ, f, Θ, s,Ϛ, w/ were spoken by a speaker who had been selected in a pilot study as being easy to lipread. The 81 stimuli were used to construct three test tapes, one where the speaker spoke slowly, one where she spoke faster, and one in which the fast tape was reversed. Coarticulatory influences were expected to be present in these stimuli. Lipreading scores and measurements of the articulations were compared in an effort to explain some of the variability in the visual perception of phonemes which was suggested by existing literature. Lipreading performance was nearly perfect for /p,f,w, Θ,u/ on all tapes in all disyllables. Lipreading performance on /t,k,tϚ,Ϛ,s,i,æ/ varied depending on phonological context, especially on the fast test tape. Variation in the identification of the less visually dominant phonemes could be directly related to coarticulatory effects revealed in the measurement of articulatory parameters (vertical and horizontal lip opening) of the visual signal. Improvement in lipreading ability throughout the task was evidenced by normal hearing subjects. The features labial, rounded, and alveolar or palatal place of articulation transmitted more information to lipreaders than did the feature continuant. It was concluded that variability in articulatory parameters resulting from coarticulatory effects in faster speech increases lipreading difficulty, especially initially. Lipreaders are sensitive to subphonemic and subvisemic variations. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate