The influence of lexical characteristics and talker accent on the recognition of English words by native speakers of Korean.

This study investigated the influences of lexical characteristics and talker accent on English spoken word recognition by first-language (L1) Korean second-language (L2) speakers of English. Stimuli were words that varied in phonological neighborhood density (PND) and word frequency (WF), produced by a L1 English speaker (L1 talker) and a L1 Korean speaker (L2 talker). Participants were 60 listeners from three groups: 20 L1 English speakers, 20 Korean L2 English speakers studying in the United States, and 20 Korean L2 English speakers studying in Korea. The 40 L2 English speakers varied widely in their estimated English proficiency. The results showed significant main effects of talkers, PND, and listener proficiency on word-recognition accuracy as well as significant interactions among stimulus talker (i.e., L1 vs L2 talker), PND, and WF and between stimulus talker and listener groups. However, we did not find that PND differentially affects word recognition in L2 learners, as had been found previously by Imai et al. [(2005). J. Acoust. Soc. Am. 117, 896-907] using the same design. Instead, our results paralleled closely those of Yoneyama and Munson [(2017). J. Acoust. Soc. Am. 141, 1308-1320], who examined L2 English speakers whose L1 was Japanese. These findings are discussed in light of the influence of L1 lexical structure on L2 phonological processing.

K-SPAN: A lexical database of Korean surface phonetic forms and phonological neighborhood density statistics.

This article presents K-SPAN (Korean Surface Phonetics and Neighborhoods), a database of surface phonetic forms and several measures of phonological neighborhood density for 63,836 Korean words. Currently publicly available Korean corpora are limited by the fact that they only provide orthographic representations in Hangeul, which is problematic since phonetic forms in Korean cannot be reliably predicted from orthographic forms. We describe the method used to derive the surface phonetic forms from a publicly available orthographic corpus of Korean, and report on several statistics calculated using this database; namely, segment unigram frequencies, which are compared to previously reported results, along with segment-based and syllable-based neighborhood density statistics for three types of representation: an "orthographic" form, which is a quasi-phonological representation, a "conservative" form, which maintains all known contrasts, and a "modern" form, which represents the pronunciation of contemporary Seoul Korean. These representations are rendered in an ASCII-encoded scheme, which allows users to query the corpus without having to read Korean orthography, and permits the calculation of a wide range of phonological measures.

Second Language Experience Can Hinder the Discrimination of Nonnative Phonological Contrasts.

BACKGROUND/AIMS: Many studies have shown that experienced second language (L2) learners are more skilled than novice L2 learners at a variety of L2 tasks, including auditory discrimination between members of L2 phonological contrasts. In this paper we argued that while L2 experience is typically beneficial when comparing the effects of more versus less experience, it is not necessarily beneficial when comparing the effects of some experience versus none. METHODS: We compared the perceptual assimilation and discrimination of the Korean sibilant fricatives /s(h)/ and /s*/ by 3 native Mandarin populations: naïve listeners, novice L2 learners (4-6 weeks of experience), and advanced L2 learners (over 2 years of experience). RESULTS: The perceptual assimilation of /s(h)/ changed as a result of L2 experience, but only in the /a/ context. It is also shown that novice L2 learners were less accurate than the naïve listeners at discriminating between /s(h)/ and /s*/ but, crucially, only in the /a/ context. CONCLUSION: The perception of /s(h)/ by L2 learners may be affected by knowledge of the L2 unavailable to naïve listeners, and some aspects of this knowledge may result in a decline in discrimination accuracy after even a very short period of L2 experience.

The perceptual assimilation of Korean obstruents by native Mandarin listeners.

The current study reports the results of a perception experiment in which 20 naive native Mandarin listeners classified and rated the goodness of Korean stops /p, t, k, p(h), t(h), k(h), p*, t*, k*/, affricates /tɕ, tɕ*, tɕ(h)/, and fricatives /s(h), s*/ in terms of Mandarin segmental categories. It was found that listeners were sensitive to the voice onset time dimension of Korean stops and the presence of aspiration in Korean affricates, but Korean lenis and aspirated obstruents were generally assimilated to a single Mandarin category because the f0 cue differentiating them is not relevant to any Mandarin segmental contrast. The affricates were perceived as alveolopalatal and postalveolar more often than alveolar. The perception of fricatives was strongly influenced by vowel context, as the two fricatives were often perceived as different categories before /a/, but as the same category more often before /i/ and /u/. The results for the affricates and fricatives may be partly explained by Mandarin phonotactic constraints that prohibit alveolar and postalveolar consonants before /i/ and alveolopalatal consonants before /a/ or /u/.

The perception and production of Korean stops in second dialect acquisition.

This study investigated the acoustic cue weighting of the Korean stop contrast in the perception and production of speakers who moved from a nonstandard dialect region to the standard dialect region, Seoul. Through comparing these mobile speakers with data from nonmobile speakers in Seoul and their home region, it was found that the speakers shifted their cue weighting in perception and production to some degree, but also retained some subphonemic features of their home dialect in production. The implications of these results for the role of dialect prestige and awareness in second dialect acquisition are discussed.

Radiofrequency transseptal catheter electrode fracture.

Transseptal puncture is performed using a long needle advanced from the femoral approach. A radiofrequency catheter has been developed that delivers a short burst of radiofrequency energy and creates a micro puncture in the interatrial septum. We describe a case in which the distal radiofrequency electrode broke and became embedded in the interatrial septum.

The Potential Role of Talker Age in the Perception of Regional Accent.

The speech signal contains potential cues to a wide range of socioindexical variables. The aim of the current study was to investigate how one variable, talker age, might interact with the perception of a theoretically independent variable, regional accent. We investigated this question specifically in the case of Korean: although many studies have reported on phonetic differences among Korean dialects and speakers' beliefs and attitudes about them, there has been virtually no research on the auditory perception of such variation. Potential acoustic cues to regional accent were measured in read sentence productions from a total of 72 male talkers in their 20s or 50s to 60s from six Korean provinces. Then, in a perception experiment, native listeners from Seoul (n = 21), Gyeongsang (n = 10), and Jeolla (n = 10) listened to the sentences and were asked to identify the talker's regional origin from among 6 provinces. Listeners' responses correlated with talker age: young talkers were disproportionately perceived as being from Seoul, and old talkers-even life-long Seoul residents-were disproportionately perceived as being from non-Seoul regions. A follow-up experiment with listeners from Seoul (n = 30) in which talker age was treated as a between-subjects factor showed an attenuated effect, suggesting that the effect of talker age on perceived regional origin may be partially driven by a contrast effect, such that the speech of older talkers is perceived as less standard-and thus coming from a non-Seoul region-when being directly compared with that of younger talkers.

The Perception and Production of Word-Initial Korean Stops by Native Speakers of Japanese.

Previous studies have shown that non-native speakers of Korean not only have difficulty producing the word-initial three-way stop contrast, but also exhibit a wide range of production patterns. Because these studies have only investigated native (L1) speakers of English and Mandarin and given the overall paucity of research on non-native Korean, it is not yet clear how dependent these findings are on the particular native language under investigation. The current paper reinforces our empirical grounding via extension to L1 speakers of Japanese. It is shown that although naïve Japanese listeners consistently perceive Korean fortis stops as voiced, and Korean lenis and aspirated stops as voiceless, novice second language learners do not produce any significant difference among the three stop categories, despite producing clear differences between their native Japanese stop categories. Unlike in previous studies of L1 speakers of English and Mandarin, there was very little inter-speaker variation, and all speakers produced all Korean stops with long lag voice onset time.

Quantifying the Robustness of the English Sibilant Fricative Contrast in Children.

PURPOSE: Four measures of children's developing robustness of phonological contrast were compared to see how they correlated with age, vocabulary size, and adult listeners' correctness ratings. METHOD: Word-initial sibilant fricative productions from eighty-one 2- to 5-year-old children and 20 adults were phonetically transcribed and acoustically analyzed. Four measures of robustness of contrast were calculated for each speaker on the basis of the centroid frequency measured from each fricative token. Productions that were transcribed as correct from different children were then used as stimuli in a perception experiment in which adult listeners rated the goodness of each production. RESULTS: Results showed that the degree of category overlap, quantified as the percentage of a child's productions whose category could be correctly predicted from the output of a mixed-effects logistic regression model, was the measure that correlated best with listeners' goodness judgments. CONCLUSIONS: Even when children's productions have been transcribed as correct, adult listeners are sensitive to within-category variation quantified by the child's degree of category overlap. Further research is needed to explore the relationship between the age of a child and adults' sensitivity to different types of within-category variation in children's speech.

Predictors of hemodynamic compromise with propofol during defibrillator implantation: a single center experience.

BACKGROUND: Intra-operative hypotension has been reported in cardiac resynchronization therapy defibrillator (CRT-D) clinical trials but this phenomenon is not well characterized. The purpose of this study was to understand the frequency and determinants of intra-operative hypotension in patients undergoing defibrillator implantations. METHODS: We retrospectively reviewed clinical data of all CRT-D implantations over a 21-month period. We compared a randomly selected contemporaneous group undergoing implantable cardiac defibrillator (ICD) implantations as a reference group. Procedure protocol involved intra-arterial blood pressure monitoring throughout the case. Lidocaine (1%) was routinely used along with propofol for sedation in all patients. Procedure time was defined as the time from initial administration of lidocaine for arterial line access, to completion of defibrillator pocket closure. Cumulative dose of propofol was calculated in each patient. Hypotension was defined as a fall in the systolic blood pressure of >or=30% from baseline or a systolic blood pressure of 3 min. CRT-D and ICD patients were divided into hypotensive and non-hypotensive subsets. RESULTS: The incidence of hypotension in the CRT-D group (N = 100) was 56%, as compared to 40% in the ICD group (N = 97). The mean duration of procedure in the CRT-D group was 114 +/- 95 min in the hypotensive subset versus 69 +/- 31.9 min in the non-hypotensive subset (p = 0.0015). The mean NYHA class in the hypotensive subset of the CRT-D group was 2.85 +/- 1.2 vs 2.2 +/- 1.5 in the non-hypotensive subset (p = 0.0179). Cumulative dose of propofol in the hypotensive subset of the CRT-D group was 386 +/- 22 mg, while that in the non hypotensive subset was 238.3 +/- 17 mg (p < 0.0001). Creatinine clearance in the hypotensive subset of the CRT-D group was 63.8 +/- 12.8 ml/min, while that in the non-hypotensive subset was 78.7 +/- 23.5 ml/min (p = 0.003). Patients in the CRT-D group who developed hypotension had a lower left ventricular ejection fraction of 21.1 +/- 10.2% versus 29 +/- 14.8% in the non-hypotensive subset (p = 0.0035). CONCLUSIONS: Hypotension is a common occurrence during defibrillator implantation under conscious sedation. Risk factors for significant hypotension include: higher NYHA class, lower left ventricular ejection fraction, lower creatinine clearance, higher doses of propofol and longer procedure times.