Communication Disorders Ph.D. Dissertations

The Role of Secondary-stressed and Unstressed-unreduced Syllables in Word Recognition: Acoustic and Perceptual Studies with Russian Learners of English

Date of Award

2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Communication Disorders

First Advisor

Laura Dilley (Advisor)

Second Advisor

Lynne Hewitt (Committee Chair)

Third Advisor

Sheri Wells-Jensen (Committee Member)

Fourth Advisor

Alexander Goberman (Committee Member)

Fifth Advisor

John Folkins (Committee Member)

Abstract

Identifying those phonological factors that native listeners rely on most when perceiving non-native speech is critical for setting priorities in pronunciation instruction. The importance of accurate lexical stress production, particularly primary stress, has been explored. However, little is known about the role of Secondary-stressed (SS) syllables and Unstressed-unreduced (UU) syllables, and the importance of their accuracy for speech perception. These questions are of relevance for Russian learners of English, who often reduce English SS and UU vowels—a phenomenon which is arguably due to the fact that only one stressed syllable per word is allowed in Russian phonology. Moreover, second language research has not addressed the issue of vowel over-reduction, which is a pattern typical of Russian learners. Low-accuracy productions of SS and UU syllables are generally not expected to lead to unintelligibility; however, they might interfere with the ease and accuracy with which speech is perceived. An acoustic study first compared realization of SS and UU syllables in words produced in isolation by six Russian learners of English and six native English speakers. Words were selected to contain low vowels and specific UU and SS syllable positions to optimally reflect vowel reduction by Russian speakers. Acoustic analyses revealed significant vowel quality and duration reductions in Russian-spoken SS and UU vowels, which were only half the duration of native English productions and significantly centralized. A subsequent psycholinguistic perceptual study investigated the degree of interference that inaccurate productions of SS and UU syllables have on native listeners' speech processing. A cross-modal phonological priming technique combined with a lexical decision task assessed speech processing of 28 native English speakers as they listened to (1) native English speech, (2) unmodified Russian speech, and (3) modified Russian speech with SS and UU syllables altered to match native productions. Unmodified UU vowels led to significant inhibition of lexical access, while unmodified SS vowels revealed less of such interference. Acoustically "improving" vowel quality and duration in UU and SS syllables greatly facilitated word recognition only for UU-syllable-containing words. A recommendation is made that UU syllables are incorporated into pronunciation instruction for Russian learners of English.

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