L2 Proficiency Effect on the Acoustic Cue-Weighting Pattern by Korean L2 Learners of English: Production and Perception of English Stops

Abstract

This study explored how Korean L2 learners of English utilize multiple acoustic cues (VOT and F0) in perceiving and producing the English alveolar stop with a voicing contrast. Thirty-four 18-year-old high-school students participated in the study. Their English proficiency level was classified as either 'high' (HEP) or 'low' (LEP) according to high-school English level standardization. Thirty different synthesized syllables were presented in audio stimuli by combining a 6-step VOTs and a 5-step F0s. The listeners judged how close the audio stimulus was to /t/ or /d/ in L2 using a visual analogue scale. The L2 /d/ and /t/ productions collected from the 22 learners (12 HEP, 10 LEP) were acoustically analyzed by measuring VOT and F0 at the vowel onset. Results showed that LEP listeners attended to the F0 in the stimuli more sensitively than HEP listeners, suggesting that HEP listeners could inhibit less important acoustic dimensions better than LEP listeners in their L2 perception. The L2 production patterns also exhibited a group-difference between HEP and LEP in that HEP speakers utilized their VOT dimension (primary cue in L2) more effectively than LEP speakers. Taken together, the study showed that the relative cue-weighting strategies in L2 perception and production are closely related to the learner's L2 proficiency level in that more proficient learners had a better control of inhibiting and enhancing the relevant acoustic parameters.

Individual differences in phonetic cue use in production and perception of a non-native sound contrast

“…Along these lines, Kang and Guion (2006) showed that native Korean speakers who had learned English later in life appeared to have merged the English voiceless and Korean aspirated categories in production; English voiced stops, on the other hand, appeared to be a distinct category from either Korean fortis or lenis stops (similar to fortis stops in terms of VOT, but similar to lenis stops in terms of f0). Similarly, Kong and Yoon (2013) showed that native Korean speakers with higher English proficiency made more effective use of VOT in distinguishing the English stop contrast, and that the high-proficiency group showed more native-English-like performance in perception as well. Further perceptual findings come from Schmidt (1996) and Park and de Jong (2008), who asked native Korean listeners to listen to English syllables and indicate the Korean consonant that best represented the syllable-initial sound.…”

“…Previous work has shown greater-than-native-like use of f0 (e.g. Kim 1994; Kang and Guion 2006; Kong and Yoon 2013); at the same time, work showing differences in L2-L1 mapping of the English to Korean contrast (e.g. Schmidt 1996; Park and de Jong 2008) suggests that there may be considerable variability in perceptual patterns.…”

“…Previous work has found that Korean speakers and listeners make use of both VOT and f0 when producing (Kang and Guion 2006; Kong and Yoon 2013) and perceiving (Kim 1994; Kong and Yoon 2013) their L2 English stop contrast, implying that the heavy use of f0 in their native contrast may transfer to their L2 sound categories. However, the group patterns shown in this previous work do not give a detailed picture of how, why, or to what extent this L1 influence is realized.…”

“…Broad differences in language experience or proficiency on a group level are often linked to differences in perception, and in general, studies that split up early vs. late learners (or more vs. less proficient speakers) show the expected pattern of more native-like cue weighting for more experienced groups. For example, Flege et al (1997) found that experienced listeners from different language backgrounds both produced and perceived L2 English vowel contrasts with more native-like cue-weighting strategies (see also Flege et al (1996); Bohn and Flege (1997); Baker and Trofimovich (2005); Kong and Yoon (2013), among many others). However, efforts to find individual correlations between proficiency and native-like perception on an individual level have proven elusive; variation in cue-weighting strategies for L2 vowel contrasts by L1 Catalan and Spanish listeners (Cebrian 2006; Morrison 2008) and for the L2 English /ɹ/-/l/ distinction (Hattori and Iverson 2009) by L1 Japanese listeners was not correlated with experience or proficiency.…”

Individual differences in perceptual adaptability of foreign sound categories

“…Interestingly, Korean speakers vary both VOT and f0 to an equal extent when distinguishing their L2 English stop contrast in production (Schertz et al, 2015), but this cue use is not necessarily reflected in their perception . The factors underlying these differences in phonetic structure are not yet known; however, recent work by Kong and Yoon (2013) suggests that listeners’ level of English proficiency plays a role, with higher-proficiency speakers using f0 less (i.e. in a more native-like way) than lower-proficiency speakers.…”