• Speech Sciences
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• v.13 no.4
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• pp.69-87
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• 2006

This study aims to describe the vowel system of present-day American English and to discuss some of its phonetic variations due to regional differences. Fifteen speakers of American English from various regions of the United States produced the monophthongs of English. The vowel duration and the frequencies of the first and the second formant were measured. The results indicate that the distinction between the vowels [c] and [a] has been merged in most parts of the U.S. except in some speakers from eastern and southeastern parts of the U.S., resulting in the general loss of phonemic distinction between the vowels. The phonemic merger of the two vowels can be interpreted as the result of the relatively small functional load of the [c]-[a] contrast, and the smaller back vowel space in comparison to the front vowel space. The study also shows that the F2 frequencies of the high back vowel [u] were extremely high in most of the speakers from the eastern region of the U.S., resulting in the overall reduction of their acoustic space for high vowels. From the viewpoint of the Adaptive Dispersion Theory proposed by Liljencrants & Lindblom (1972) and Lindblom (1986), the high back vowel [u] appeared to have been fronted in order to satisfy the economy of articulatory gesture to some extent without blurring any contrast between [i] and [u] in the high vowel region.

• Speech Sciences
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• v.4 no.1
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• pp.7-17
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• 1998

The purpose of this preliminary study on Korean vowel duration was to find how different syllable types and kinds of plosives influence vowel duration. The vowel duration of the Front Mid and Low vowels (/$\varepsilon$/(에), /e/(어), /${\ae}$/(애), /a/(아)) was found to be longer than that of High and Back vowels (/i/(이), /i/(으), /u/(우), /o/(오)). Compared with single vowels (V), Vowels followed by a consonant (CV) were shortened by 79.3% and vowels between consonants (CVC) were shortened by 38.5%, respectively. These results suggest that the influence of consonants upon Korean vowel duration depend on syllble types and the manner or place of articulation.

• Phonetics and Speech Sciences
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• v.1 no.4
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• pp.3-9
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• 2009

Acoustically English vowels are defined primarily by formant values. The measurements of the values have been usually made at a few time points of the vowel segment despite the fact that the majority of English vowel formants vary dynamically throughout the segment. This study attempts to collect acoustic data of the nine English vowels published by Hillenbrand et al. (1995) online and to examine the acoustic features of the English vowels for phoneticians and English teachers. The author used Praat to obtain the data systematically at six equidistant timepoints over the vowel segment. Obvious errors were corrected based on the spectrographic display of each vowel. Results show that the first two formant trajectories are important to separate the nine vowels within the front- or back-vowel groups. The third formant trajectories appear comparable except those of the high vowels. Second, the back vowels leave longer traces on the vowel space toward the locus of the following consonant /d/. Third, each vowel has inherent duration, pitch, and intensity patterns. The results match the findings of Yang (2009). From the results, the author concludes that dynamic spectral changes are important in specifying acoustic characteristics of English vowels. Further studies on the application of the vowel trajectories to English pronunciation lessons or on perceptual experiment of synthesized vowels are desirable.

• Phonetics and Speech Sciences
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• v.3 no.4
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• pp.13-21
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• 2011

The present study investigated the effects of two different sources of prosodic strengthening, i.e., boundary and accent, in the articulation of English high front vowels, /i/ and /I/. The vowels were investigated in vowel-initial ('eat' vs. 'it'), /h/-initial ('heat' vs. 'hit') and /p/-initial words ('Pete' vs. 'pit'), which were placed in varying prosodic conditions. Using Electromagnetic Articulograph (EMA), the tongue dorsum positions in the x and y dimensions, the lip opening and the jaw opening (lowering) were measured. With respect to the boundary-induced strengthening, results showed that /i/ and /I/ in vowel-initial words ('eat' - 'it') are produced with a higher tongue position in the domain-intial than domain-medial positions. The fact that the vowels only in the vowel-initial condition showed the domain-intial strengthening (DIS) effect suggests that the DIS effect is localized mainly to the initial position (the locality account). As for the accent-induced strengthening, vowels were produced with a more fronted tongue position and larger lip opening in accented than unaccented positions. This suggests that the presence of accent increases overall sonority of the vowels in various prosodic contexts, and enhances primarily the frontedness of the front high vowels. Taken together, the results indicate that the two types of prosodic strengthening are articulatorily realized differently, supporting the view that they are encoded separately in the speech planning process. The present study also showed the distinction between the two high front vowels in the tongue position (in both the frontedness and the height dimensions), while the jaw did not seem to contribute to the distinction robustly, suggesting that the tongue contributes more in distinguishing the two vowels than the jaw does.

• Phonetics and Speech Sciences
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• v.6 no.4
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• pp.17-26
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• 2014

The present study examined epenthetic vowels produced by Korean learners of English in read sentences, in terms of acoustic measures and extra-phonological factors. The results demonstrated three main findings. First, epenthetic vowels had relatively high F1 values and a wide range of F2 values. Most of the epenthetic vowels were inserted near Korean high central vowels, but some vowels were inserted near front vowels due to co-articulation with surrounding vowels. Second, vowel epenthesis was affected by the context. The results showed that the epenthesis was frequently seen with word junctions between obstruents (e.g., stops-fricatives). Third, Korean learners were not affected by English background and were very weakly affected by orthography. English experience, which is one of the extra-phonological factors, was not related to epenthesis production. However, orthography, the other extra-phonological factor, very weakly affected the amount of epenthesis production. Nine percent of all epenthesis production was affected by the English past-tense suffix '-ed'; approximately 70% of the participants were affected by this suffix. The findings of the present study contributed to understanding vowel epenthesis. First, the study revealed that the epenthetic vowels produced by Korean learners of English were close to the high central vowel, supporting previous studies that the epenthetic vowel is quite close to the shortest vowel. Second, the study examined the various phonetic environments of epenthetic vowels, revealing that vowel epenthesis occurred more frequently in a certain phonetic circumstance.

• Proceedings of the KSPS conference
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• 2002.03a
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• pp.54-62
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• 2002

• Phonetics and Speech Sciences
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• v.1 no.4
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• pp.39-46
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• 2009

This study compares the perception of English high tense and lax vowels (/i, I, u, $\mho$/) by English speakers and Korean speakers of English. The four vowels were produced in /hVd/ context by a native speaker of English, and each word's vowel duration was manipulated to range from 170ms to 290ms in 30ms increments. Two English speakers and six Korean speakers of English were asked to listen to pairs of tense and lax vowel words with manipulated vowel durations and to identify the pair by choosing either heed-hid or hid-heed for front vowels and either who'd-hood or hood-who'd for back vowels. The results show that English speakers distinguished tense vowels from lax vowels with 100% accuracy regardless of the different durations, compared to 62% accuracy for Korean speakers of English. Most errors occurred for lengthened lax vowels and shortened tense vowels. The results of this study demonstrate that Korean speakers mainly rely on vowel duration as a cue to discriminate the tense and lax vowels. The theoretical and pedagogical implications of this finding are discussed.

• Speech Sciences
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• v.12 no.1
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• pp.75-87
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• 2005

In this study I investigate how native Korean listeners perceive English vowels /i/, /I/, and /$\epsilon$/. I extend Flege et al's (1997) study with synthesized /i/-/I/ and /I/-/$\epsilon$/ continua, and apply the results to Flege's (1995) Speech Learning Model (SLM). The statistical results show that native speakers of English rely more on spectral steps than on vowel duration when they identify the /i/-/I/ continuum, whereas native speakers of Korean rely more on vowel duration than on spectral steps when they identify the same continuum. In the case of the /I/-/$\epsilon$/ continuum, both groups rely on spectral steps when they identify the /$\epsilon$/, which supports the SLM; Koreans identified the /$\epsilon$/ categorically since Korean has the equivalent vowel. However, there was not statistical difference between Korean subjects with more English experience (KE) and those with less English experience in the identification of both continua. This contradicts the SLM, which posits that experienced L2 learners are better than inexperienced L2 learners in perception of L2 sounds. The exact nature of this should be further investigated in the SLM.

• Phonetics and Speech Sciences
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• v.5 no.2
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• pp.53-58
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• 2013

The purpose of this study is to compare the first two vowel formants of the stressed and unstressed English vowels produced by ten young males (in their twenties and thirties) and ten old males (in their forties or fifties) from the Buckeye Corpus of Conversational Speech. The results indicate that the stressed and unstressed vowels, /i/ and $/{\ae}/$ in particular, from the two groups are different in their formant frequencies. In addition, the vowel space of the unstressed vowels is somewhat smaller than that of the stressed vowels. Specifically, the range of the second formant of the unstressed vowels and that of the first formant of the unstressed front vowels were compressed. The findings from this study can be applied to the pronunciation training for the Korean learners of English vowels. We propose that teachers of English pay attention to the stress patterns of English vowels as well as their formant frequencies.

• Phonetics and Speech Sciences
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• v.5 no.3
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• pp.31-38
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• 2013

This study investigated the influence of English vowel pronunciation training to English word-initial stop pronunciation. For that purpose, VOT values of English stops produced by twenty Korean English learners(five Youngnam dialect male speakers, five Youngnam dialect female speakers, five Kangwon dialect male speakers, and five Kangwon dialect female speakers) were measured using the Speech Analyzer and their post-training production was compared with their pre-training production. The result shows that post-training VOT values of voiced stops became closer to those of native English speakers in all four groups. Hence, it can be inferred that vowel pronunciation training is effective for correcting pronunciation of voiced vowels by analyzing the change of the quality of following vowels(especially low vowels) and the degree of giving stress.