• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.17 no.2
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• pp.107-110
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• 2006

Background and Objeetives : There are few studies reported that specifically examined the voice onset time(VOT) in patients with bilateral vocal nodules. The purpose of this study was to study the characteristics of voice onset in patients with bilateral vocal nodules. Materials and Methods : 52 female patients with bilateral vocal nodules were examined, aged from 20 to 54 years, and were compared with 25 normal female control group. All subjects produced five repetitions of the voiceless stops $/p^h,\;t^h\;k^h/$ in vowel context /ai_a/. VOT was measured by the time between the release of the stops and the onset of voicing. Results : VOTs of the voiceless stops $/p^h/\;and\;/t^h/$ in patients with bilateral vocal nodules were significantly shorter than those of normal subjects. VOT of the $/k^h/$ in them was shorter than those of normals, but the difference was not significant. This results showed that VOTs of the voiceless stops in patients with bilateral vocal nodules were shorter than those of normal subjects. Conclusion : The rapid onset of voicing in patients with bilateral vocal nodules might be associated with increased laryngeal muscle tension by hard glottal attacks. We suggest that VOT can be a clinically useful acoustic parameter for evaluating voice in patients with bilateral vocal nodules.

• Proceedings of the KSPS conference
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• 1996.10a
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• pp.390-398
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• 1996

Acoustic analysis study was performed on 20 normal subjects by speaking nonsense syllables composed of Korean bilabial stops(/p, $p^{*}$/, ph/) and their Preceding and/or following vowel /a/(that is, [pa, $p^{*}a$, pha, apa, $ap^{*}a$, apha]) with an ultraminiature pressure sensor in their mouths. Speech materials were phonated twice, once with a moderate voice, another time with a loud voice. The acoustic signal and intraoral pressure were recorded simultaneously on computer. By these procedures, we were to measure the intraoral pressure, closure duration and VOT of Korean bilabial stops, and to compare the values one another according to the intensity of phonation and the position of the target consonants. Intraoral pressure was measured by the peak intraoral pressure value of its wave; closure duration by the time interval between the onset of intraoral pressure build-up and the burst meaning the release of closure; Voice onset time(VOT) by the time interval between the burst and the onset of glottal vibration. Heavily aspirated bilabial stop consonant /ph/ showed the highest intraoral pressure value, unaspirated /p$^{*}$/, the second, slightly aspirated /p/, the lowest. The syllable initial bilabial stops showed higher intraoral pressure than word initial stops, and the value of loudly phonated consonants were higher than moderate consonants. The longest closure duration period was that of /$p^{*}$/ and the shortest, /p/, and the duration was longer in word initial position and in the moderate voice. In VOT, the order of the longest to shortest was /ph/, /p/, /$p^{*}$/, and the value was shorter when the consonant was in intervocalic position and when it was phonated with a loud voice.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.17 no.2
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• pp.98-102
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• 2006

Background and Objectives : Voice onset time(VOT) is defined as the time interval from oral release of a stop consonant to the onset of glottal pulsing in the following vowel. VOT is a temporal characteristics of stop consonants that reflects the complex timing of glottal articulation relative to supraglottal articulation. Stop consonants are characterized by creation of a pressure difference across a complete occlusion in the vocal tract, followed by a sudden release 'burst' due to opening that occlusion. The objects of this study is to evaluate a usefulness of voice onset time in the assessment of voice disorderd patients. Subjects : Subjects were 20 adults with normal voice and with benign laryngeal disorders. Subjects with voice disorders represented the following vocal pathologies : vocal polyp, vocal nodule, Reinke's edema and unilateral vocal fold paralysis(UVFP). Control subjects were matched for age (21-40 yews old) and sex(male) with the voice disorders subjects and had normal vocal qualities with no history of voice disorders. Methods : Each voice-disordered and matched control subject read the test passages containing three types of Korean bilabial consonants. VOT measures were made for the initial $/p/p^h/\;and\;/p'/$. VOT was measured using acoustic waveform or wide band spectrogram. Results : For each voiceless stop consonants, there was a significant difference in VOT between the voice disordered and normal subjects. The mean VOTs of the lax stops in UVFP was significantly shorter than those of control subjects in the UVFP. The mean VOTs of the aspirated stops in the vocal polyp and nodule were longer than those of control subjects, but not significant. The mean VOTs of the glottalized in voice disordered groups were longer than those of control subjects, and significant statistically in the UVFP. Conclusions : VOT may be a clinically useful acoustic parameter in the assessment of voice disordered patients, especially in the unilateral vocal fold paralysis.

• Speech Sciences
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• v.11 no.2
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• pp.71-87
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• 2004

Korean has a pair of voiceless fricatives, whose laryngeal manifestation comes in parallel to stops and affricates with a three-way lexical contrast. Prior phonetic studies by Kagaya (1974), Iverson (1983), and Kang (1999, 2000) point out /s/ is associated with multiple characteristics of the larynx shared with not only the lax but also the aspirated series, whereas /s' / carries a laryngeal distinction typical of the tense consonants. The complex dual nature of /s/ is again supported by a psycholinguistic study by Kang (2004), as /s/ was found to interact with /$c^h$/ (17% of the time) as well as /c/ (57%) in speech errors. In addition, a recent work by Cho and Lee (2003) notes an interesting chain shift case in the acquisition of the fricatives. Although they observed a significant phonological pattern between child English and Korean, Cho and Lee's description of acquiring fricatives is far from being precise from the perspective of phonetics. From a longitudinal study of recorded tapes by two children at 1;7-3;8 and 1;7-2;1 respectively, I found that /s' / was usually substituted into tense noncontinuants in young children's early production as predicted, whereas /s/ having both lax and aspirated-like glottal properties revealed a complicated pattern of substitutions into lax, tense, and aspirated noncontinuants with a varying degree of preference relative to the subjects. The current acquisition study supports the previous claims concerning fricatives in other languages, showing that their acquisition comes after stops. Besides, it also notes that Korean fricatives are subject to a series of phonological processes called stopping, affricating, tensifying and palatalizing during the transitional period of phonological development by young children. Moreover, between the two voiceless types, /s/ was acquired earlier than /s'/ as the unmarked segment.

• Speech Sciences
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• v.12 no.2
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• pp.139-149
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• 2005

The purpose of this study was to propose a preliminary norm for 'Korean-Test of Articulation for Children(K-TAC)'. The K-TAC was designed to test 19 Korean consonants in various phonetic contexts through 37 words. We collected the data of 220 normally developing children aged 2;6(years;months) to 6;5. We analyzed the mean percentage of consonants correct and the age of acquisition for K-TAC. The results were as follows: first, The mean percentage was over 60% at late 2 years of age, over 80% at th age of 3, and over 90% after the age of 4. There were significant differences among age groups. Second, based on the criterion of correct production by 75% of children, Korean children acquired stops and nasals except for SF velars, glottal fricative, SF liquid and affricates by late 2 or 3 years of age. After that they acquired SF velars at the age of 4 and SI liquid at the age of 5. However, they could not acquire alveolar fricatives by the age of late 6. Third, if the distorted sounds were scored as correct, they acquired SI liquid at 4 years of age and alveolar fricatives at 5 years of age.

• Phonetics and Speech Sciences
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• v.7 no.1
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• pp.39-45
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• 2015

Changes in speech production in normal elderly might be subtle and gradual. Therefore, an acoustic analysis is appropriate to identify the effect of aging on speech. For this purpose, this study examined four speech parameters; voice onset time (VOT), VOT range, $f_0$ of following vowel($f_0FV$), and $f_0FV$ difference in two age groups, old (mean age 74.57 yrs.) and young (m: 27.43 yrs.). The results show that compared to the older group the younger demonstrated significantly shorter VOTs in lenis and longer in aspirated stop. VOT ranges were relatively broad and consequently overlapped between the phonation types (e.g., lenis, fortis, aspirated). The $f_0FV$ values in the older group which are an integral parameter with VOT were lower compared with the young group. The $f_0FV$ differences in the old female group were significantly narrower than the young female group, therefore, clear distinction became difficult. In conclusion, contrast in temporal information was obscured, and the domain of glottal information was diminished on stop consonants in Korean elderly. The findings suggest that central/peripheral changes by aging could lead to a deficit in coordination between phonation and articulation.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.11 no.1
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• pp.104-112
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• 2000

An evaluation of voice disorder has two methods. One is a perceptual analysis and the other is an acoustic analysis. All of these methods are just focused on sustained vowel. The analysis of conversational speech levels in voice disorder has not been achieved enough. The purpose of the present study is to compare two syllable words and sustained vowel in the vocal polyp patients and normal male speakers and to be applied on the vocal assessment and the voice therapy as a basic data. fifteen male patients with vocal polyp were the subject group. Fifteen healthy male were the control group for this study. The voices of the subject and control group, saved in MDVP of CSL were analyzed by its own analysis program. As a results, in subject group, the voice qualities between the vowel following lenis stop and the sustained vowel had no differences, and the voice qualities were different significantly between the vowel following heavily aspirated stop and the sustained vowel. In the control group the vowel fllowing stops and sustained vowel had also many differences in their voice quality, especially significant between the vowel following glottal stop and e sustained vowel.