• Speech Sciences
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• v.13 no.3
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• pp.49-65
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• 2006

Recently, several theories on the digital speech signal processing expanded the communication boundary between human beings and machines drastically. The aim of this study is to collect dialectal speech in Korea on a large scale and to establish a digital speech data base in order to provide the data base for further research on the Korean dialectal and the creation of value-added network. 528 informants across the country participated in this study. Acoustic characteristics of vowels and consonants are analyzed by Power spectrum and Spectrogram of CSL. Test words were made on the picture cards and letter cards which contained each vowel and each consonant in the initial position of words. Plot formants were depicted on a vowel chart and transitions of diphthongs were compared according to dialectal speech. Spectral times, VOT, VD, and TD were measured on a Spectrogram for stop consonants, and fricative frequency, intensity, and lateral formants (LF1, LF2, LF3) for fricative consonants. Nasal formants (NF1, NF2, NF3) were analyzed for different nasalities of nasal consonants. The acoustic characteristics of dialectal speech showed that young generation speakers did not show distinction between close-mid /e/ and open-mid$/\epsilon/$. The diphthongs /we/ and /wj/ showed simple vowels or diphthongs depending to dialect speech. The sibilant sound /s/ showed the aspiration preceded to fricative noise. Lateral /l/ realized variant /r/ in Kyungsang dialectal speech. The duration of nasal consonants in Chungchong dialectal speech were the longest among the dialects.

• Phonetics and Speech Sciences
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• v.2 no.2
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• pp.43-50
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• 2010

English vowels can be divided into monophthongs and diphthongs depending on the number of vocal tract shapes. Diphthongs are usually produced with more than one shape. This study attempts to collect acoustical data of English diphthongs published by Hillenbrand et al.(1995) online and to examine acoustic features of the diphthongs for phoneticians and English teachers. Sixty three American males and females were chosen after excluding those subjects with different target vowels or ambiguous formant tracks. The author used Praat to obtain the acoustical data systematically at eleven equidistant timepoints over the diphthongal segment. Obvious errors were corrected based on the spectrographic display of each diphthong. Results show that the formant trajectories of the diphthongs produced by the American males and females appeared quite similar. When the female formant values were uniformly normalized to those of the males, almost a perfect collapse occurred. Secondly, the diphthongal movements on the vowel space appeared not linear due to the coarticulatory gesture for the following consonant. Thirdly, the average duration of the diphthongs produced by the females was 1.156 times longer than that of the males while the pitch ratio between the two groups turned out to be 1.746 with a similar contour over measurement points. The author concludes that English diphthongs produced by various groups can be compared systematically when the acoustical values are obtained at proportional timepoints. Further studies will be desirable on the comparison of English diphthongs produced by native and nonnative speakers.

• Phonetics and Speech Sciences
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• v.4 no.3
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• pp.85-92
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• 2012

It is a well-known phenomenon that vowel duration in English is generally longer before a voiced stop than a voiceless one. Past research has postulated that the closure duration of the voiceless stop is generally longer than that of the voiced stop and that the duration of a preceding vowel is determined complementarily by the closure duration of the stop. To shed further light on the phenomenon, this study examined fourteen native speakers of American English who read the monosyllabic words [bVC] (V = [i, ɪ, eɪ, ɛ, æ, ʌ, ɑ], C = [t, d]). First, we found that mean vowel duration was 38 ms longer before the voiced stop than the voiceless (mean duration ratio = 1.24). Second, mean closure duration of the voiced stop was only shorter by 5 ms compared to the voiceless stop (mean duration ratio = 0.97). Therefore, for our subjects, vowel duration was not determined complementarily by the closure duration of the following stop. Third, vowels with longer inherent durations (viz., tense, diphthong, and low vowels) tended to show larger duration ratios in the voiced and voiceless contexts than the vowels with shorter durations (viz., lax vowels). This indicates that the lengthening of inherently shorter vowels before a voiced stop is limited in order to avoid overlapping with longer vowels in the duration range. Fourth, there was no significant gender difference in vowel duration ratios in the contexts of voiced and voiceless stops. Finally, considerable individual differences were found in the vowel and consonant duration ratios.

• Journal of Convergence for Information Technology
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• v.8 no.1
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• pp.37-42
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• 2018

This study focuses on investigating and comparing the lengths of the five words, vowels, and the ratio of the length of vowels to that of words among the Korean college students with the English native speaker. English sentences were read and recorded by Korean subjects to do this experiment. The vowel lengths were measured from a sound spectrogram, the Praat software program, and these data were analyzed through statistical analysis. I could easily tell that there were differences between the groups and they were significant. In the English front low vowel /${\ae}$/, I was able to find out that native subjects pronounced differently from Korean subjects, and the differences were significant. However, the pronunciation of the English diphthong /ai/, native subjects pronounced significantly shorter than Korean subjects.

• Journal of Digital Contents Society
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• v.13 no.3
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• pp.279-290
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• 2012

The purpose of this experimental study is to investigate and compare the vowel lengths of the English diphthongs, /eɪ/ and /aɪ/, and the front low vowel /æ/ among English-speaking natives with Korean college students using the Praat software program. To do this English sentences were uttered and recorded by twelve subjects, six Korean subjects and six English-speaking native subjects. All the subjects are female and their age ranges from 23 to 35. Acoustic features(duration) were measured from a sound spectrogram with the help of the Praat software program and analyzed through statistical analysis. Results showed that the vowel lengths of the English diphthongs and the front low vowel between native English speakers and Korean collegians were different. In the pronunciation of the diphthongs /eɪ/ and /aɪ/, Korean subjects pronounced longer than native subjects did, but the difference was not significant. However, in the pronunciation of the English front low vowel /æ/, native subjects pronounced significantly longer than Korean subjects did. From the data of the overall sum of words and vowels between the two subject groups, we were able to find out that the differences of lengths of both the three words and the two diphthongs /eɪ/ and /aɪ/ were not significant, but those of /æ/ were significant.