Tae-Hwan Choi

The acquisition of phonetic details: Evidence from the production of English reduced vowels by Korean learners

The purpose of this study was to evaluate the acquisition of non-contrastive phonetic details of a second language. Reduced vowels in English are realized as a schwa or barred- i depending on their phonological contexts, but Korean has no reduced vowels. Two groups of Korean learners of English who differed according to the experience of residence in English-speaking countries and a group of English native speakers were asked to produce English reduced vowels in word-initial, word-internal and word-final positions. The mean duration ratios, and the mean values and distribution patterns of F1/F2 of the reduced vowels were compared between the three groups, which revealed that Korean learners without residence experience tended to produce each variant of English reduced vowels as the corresponding full vowels, whereas those with experience displayed similar patterns to the natives. The present results suggest that it is possible for second language (L2) learners to learn the statistical properties in L2.

The influence of spelling on the production and storage of words with allophonic variants of /h/ in Korean

This study examined the role of orthography in the production and storage of spoken words. Korean speakers learned novel Korean words with potential variants of /h/, including [ɦ] and o. They were provided with the same auditory stimuli but with varying exposure to spelling. One group was presented with the letter for o ( ), the second group, the letter for [ɦ] ( ), and the third group, auditory input only. In picture-naming tasks, the participants presented with produced fewer words with [ɦ] than those presented with . In a spelling recall task, the participants who were not exposed to spelling displayed various types of spellings for variants, but after exposure to spelling, they began to produce spellings as provided in the task. These results suggest that orthographic information influences the production of words via an offline restructuring of the phonological representation.

Perception and production of English stops by tonal and non-tonal Korean dialect speakers

This study examines whether relative weightings of voice onset time and onset F0 in Korean tonal vs non-tonal dialects affect the production and perception of English voiced and voiceless stops. Following Shultz et al. [(2012). J. Acoust. Soc. Am. 132, EL95-EL101], discriminant function analysis and logistic regression were conducted to calculate each speakers relative weightings of these two cues in the production of target words and the labeling of the synthesized tokens according to these cues, respectively. The results demonstrated that the acquisition of second language (L2) contrasts is influenced by native language dialects, and production and perception are not developed in parallel in L2 acquisition.

The Interlanguage Speech Intelligibility Benefit (ISIB) of English Prosody: The Case of Focal Prominence for Korean Learners of English and Natives

This study investigated the speech intelligibility of Korean-accented and native English focus speech for Korean and native English listeners. Three different types of focus in English, broad, narrow and contrastive, were naturally induced in semantically optimal dialogues. Seven high and seven low proficiency Korean speakers and seven native speakers participated in recording the stimuli with another native speaker. Fifteen listeners from each of Korean high & low proficiency and native groups judged audio signals of focus sentences. Results showed that Korean listeners were more accurate at identifying the focal prominence for Korean speakers` narrow focus speech than that of native speakers, and this suggests that the interlanguage speech intelligibility benefit-talker (ISIB-T) held true for narrow focus regardless of Korean speakers` and listeners` proficiency. However, Korean listeners did not outperform native listeners for Korean speakers` production of narrow focus, which did not support for the ISIB-listener (L). Broad and contrastive focus speech did not provide evidence for either the ISIB-T or ISIB-L. These findings are explained by the interlanguage shared by Korean speakers and listeners where they have established more L1-like common phonetic features and phonological representations. Once semantically and syntactically interpreted in a higher level processing in Korean narrow focus speech, the narrow focus was phonetically realized in a more intelligible way to Korean listeners due to the interlanguage. This may elicit ISIB. However, Korean speakers did not appear to make complete semantic/syntactic access to either broad or contrastive focus, which might lead to detrimental effects on lower level phonetic outputs in top-down processing. This is, therefore, attributed to the fact that Korean listeners did not take advantage over native listeners for Korean talkers and vice versa.

Speech Intelligibility of Korean EFL Learners: Role of Proficiency, Text Type and Text Length

The purpose of this study was to investigate whether and to what extent the intelligibility of Korean EFL learners’ speech at the text level is affected by their English proficiency, text type, and text length. Various speech materials produced by native English speakers and two Korean EFL speaker groups (high vs. low proficiency) were presented to native English listeners and two Korean EFL listener groups, respectively, for comparison of intelligibility scores. The results showed that the listeners’ overall proficiency played the most critical role in determining the level of speech intelligibility for all speaker groups, regardless of the type and length of speech materials. The speakers’ proficiency level in terms of pronunciation, however, had no significant effect. As for the text type, dialogue texts were consistently more intelligible than monologues to all listener groups while the effect of text length varied depending on the text type. These results suggest that L2 learners’ speech intelligibility needs to be examined within the context of natural L2 text beyond word- and sentence-level utterances in consideration of the interaction of text-related features and other learner variables. Some pedagogical implications are also discussed.