• 대한음성학회지:말소리
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• 제60호
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• pp.67-84
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• 2006

The purpose of this study is to find some acoustic parameters on frequency domain to distinguish the Korean nasals, $/m,\;n,\;{\eta}/$ from each other. The new parameters are devised on the basis of LTAS (Long Term Average Spectrum). The maximum peak amplitude and the relevant formant frequency are measured in low and high frequency range, respectively. The frequency of spectral valley and its energy level are also obtained in the specific frequency range of the spectrum. Spectral slope, total energy value in specific frequency range, statistical distribution of spectral energy like centroid, skewness, and kurtosis are suggested as new parameters as well. The parameters that show statistically significant differences across nasals are summerized as follows. 1) in syllable initial positions: the total energy value from 1,500 to 2,200 Hz(zeroENG); 2) in syllable final positions: the peak amplitude of the first formant(peak1_a), the formant frequency with maximum peak amplitude from 4,000 to 8,000 Hz(peak2_f), the maximum peak amplitude of the formant frequency from 4,000 to 8,000 Hz(peak2_a), and the total energy value from 1,500 to 2,200 Hz(zeroENG).

• 대한후두음성언어의학회지
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• 제8권2호
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• pp.210-216
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• 1997

Many tools have been used to evaluate the voice abnormalities of velopharyngeal insufficiency(VPI). The aim of study was to obtain the objective evaluation method of VPI by comparing the acoustic and nasalance data of experimentally induced VPI group and those of normal control group. Ten healthy young men were included in this study Mild and severe VPI were experimentally induced by retracting velopharyngeal movement. Using the nasometer, we obtained the nasalance score of the sustained oral vowels and those of three types of nasometer passages and the slope scores of nasogram of nasal words. And we analysed the change of formant frequencies for the sustained oral vowels and the changes of various parameters of hyper-tnasality by the computerized speech analysis system. The nasalance score of sustained /a/ was increased significantly in VPI conditions. There was no changes in the slope score of nasogram. On the acoustic speech analysis, the second formant frequencies of vowel /e/ and /i/ were decreased significantly in VPI conditions. This results suggested that the measurement of nasalance score and formant frequency might be useful in the evaluation of VPI.

• 말소리와 음성과학
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• 제6권2호
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• pp.55-64
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• 2014

This study measured formant bandwidths of profound hearing impaired children and examined the characteristics of their articulation. For this study, 10 cochlear implanted children(CI), 10 hearing aid children(HA) and 10 normal hearing children(NH) were asked to read 7 Korean vowels(/ɑ, ʌ, o, u, ɯ, i, ɛ/). The subjects' readings were recorded by NasalView and analyzed by Praat. The analysis of the formant bandwidths explains the degree of vocal fold opening and the characteristics of radiation. Through the analysis of formant bandwidth, we can see that the hearing-impaired maintain vocal fold tension when they speak high vowels and characteristics of radiation. Narrower B1 means better maintain vocal fold tension, wider B2 means more front and wider B3 means the rounder lips. CI's B1 was widest and NH's was narrowest. And females' B1 was wider than males'. Among vowels, B1 of /a/ was widest, and B1 of /i/ was narrowest. In the case of B2, HA and NH's B2 was wider than CI's. Females' B2 was wider than males'. And B2 of /i/ was widest, and B2 of /ʌ/ was narrowest. In the case of B3, NH's was widest, and CI's was narrowest. Males' was wider than females'. Among vowels, B3 of /o/ was widest, and B3 of /ɛ/ was narrowest. As a result, first, through the analysis of B1, we can find that NH and males could better maintain vocal fold tension than the hearing-impaired or females, and all children articulate /i/ with vocal fold tension than other vowels. Second, through the analysis of B2, NH and HA articulate vowels with the weaker rounded than CI does. And females articulate vowels with the weaker rounded than males do. Third, through the analysis of B3, NH articulate vowels with the rounder than HA or CI do, and males articulate vowels with the rounder than females do. Through the results, we can expect that the analysis of formant bandwidth will be applied to the therapy of articulation for the hearing-impaired with hearing aids or cochlear implant.

• 대한구순구개열학회지
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• 제8권1호
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• pp.45-52
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• 2005

Velopharyngeal Insufficiency(VPI); the failure of velum, the lateral wall and the posterior pharyngeal wall to separate the nasal cavity from pharyngeal cavity during speech, can be caused by congenital conditions include cleft palate, submucous cleft palate and congenital palatal insufficiency. Speech problems of VPI are characterized by hypernasality, nasal air emission, increased nasal air flow and decreased intelligibility. These speech problems of VPI can be treated with the surgical procedure, the application of temporary prosthesis and speech therapy. Biofeedback technique with Nasometer is a speech treatment method of VPI that commonly used as one component of a comprehensive procedure for improvement of speech in patients with VPI. In this article describes a case of VPI treated by biofeedback technique with Nasometer; which showed satisfactory result in nasalance and formant analysis after the speech therapy during 9 months.

• 대한후두음성언어의학회지
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• 제4권1호
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• pp.24-32
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• 1991

Cleft palate or velopharyngeal incompetence shows many disorders and disabilities affecting speech transmission. including distortion. substitution. and the nasalization of the vowels. The nasalized vowels are produced primarily by lowering of the velum. resulting in opening a side passage for the air flow through the nasal cavity. These abnormal movements give rise to complex modification of the physical property of the sound or in the sound spectrum. The authors employed Sonagraph$^{\circledR}$ as a sound analyzer in order to ascertain the features which characterize the nasalization of vowels. Twenty healthy Korean male adult voluteers were analyzed in artificial conditions of anterior and posterior nasal obstruction. and velo-pharyngeal incompetence. The results were as follows : 1) Fundamental frequency was not changed by nasal obstruction or velopharyngeal incompetence. 2) There was no significant difference of the formant intensity between normal and nasal vowels. 3) In VPI, a decrease of the frequency of $F_2$ was observed in /e/ and /i/ vowels(p<0.001). 4) In VPI, the $F_2$ was frequently missed in /o/ and /u/ vowels. 5) In the consonant spectra of VPI, the 'release burst' was usually not observed.

• 음성과학
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• 제2권
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• pp.67-88
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• 1997

The aim of this study is to develop an assessment program of speech rehabilitation for children having some language and speech disorders. Patients of dysarthria, tonsillectomy, tonsilhypertrophy, and nasal obstruction were selected for this experimental clinical phonetic study. Formant variations ($F_1\;&\;F_2$) show pre- and post-operation differences in tonsillectomy and cleft palate patients. Nasal formants ($NF_1\;&\;NF_2$) show pre- and post-operation differences in nasal obstruction. The articulation reaction time (ART) as a parameter was used to assess Voice Onset Time(VOT). It was shown longer duration for hypokinetic dysarthria and shorter for atoxic dysarthria.. The diadochokinetic rate was measured by Visi-pitch. Lower diadochokinetic rate appeared to spastic and dysarthria in comparison with the control group. It was shown that the nasalance of tonsilhypertrophy, nasal obstruction, and cleft palate patients was seen to increase after operation. In addition, the assessment of nasality can be measured only by simple vowels such as /a/ and /i/.

• 음성과학
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• 제9권4호
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• pp.201-214
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• 2002

In the Japanese language, there is a phonological contrast between not only initial stops, but also non initial in voiced and voiceless sounds. But in the Korean language, voiced sounds do not appear in the initial. Due to this, pronunciation of voiced sounds in the initial will be difficult for Korean. Through this research, I analyzed the minimal pairs by voiced/voiceless sounds of Japanese and Korean, and perception experiment in which Japanese listened to Korean speakers' pronunciations. Japanese pronunciations showed distinct acoustic differences between voiced and voiceless stops, especially in VOT. The duration of vowels after voiced stops was longer than that of voiceless ones. Vowel pitches after voiceless stops were higher. On the other hands, Korean showed three patterns of voiced sounds. There were-VOT values as native speakers, +VOT, and nasal formant tended to occur before prenasalized stops. Koreans pronounced voiceless sounds in strong aspirated, unaspirated, or tense sounds. Finally, Japanese judged sounds with not only -VOT values and prenasalized, but also with +VOT values as voiced. This suggests that we may not consider VOT values as the unique feature of voicing, and that such other phonetic characteristics as the following vowel lengthening should be included here.

• 대한인간공학회지
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• 제10권1호
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• pp.3-10
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• 1991

The teach pendant and keyboard have been used as an input device of control command in human-robot sustem. But, many problems occur in case that the usef is a novice. So, speech recognition system is required to communicate between a human and the robot. In this study, Korean voice commands, eitht robot commands, and ten digits based on the broad phonetic analysis are described. Applying broad phonetic analysis, phonemes of voice commands are divided into phoneme groups, such as plosive, fricative, affricative, nasal, and glide sound, having similar features. And then, the feature parameters and their ranges to detect phoneme groups are found by minimax method. Classification rules are consisted of combination of the feature parameters, such as zero corssing rate(ZCR), log engery(LE), up and down(UD), formant frequency, and their ranges. Voice commands were recognized by the classification rules. The recognition rate was over 90 percent in this experiment. Also, this experiment showed that the recognition rate about digits was better than that about robot commands.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1991년도 제25차 학술대회 연제순서 및 초록
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• pp.21-21
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• 1991

구개열이나 구개부전이 있는 경우, 흔히 비 정상적인 비음을 접할 수 있는데 이러한 구조이상과 구음이상간의 관계를 밝히는데 있어서 비음에 대한 객관적인 평가방법이 요구된다. 여러 객관적 지표로서의 가능성 중에 음향학적 분석이 많이 시행되었는데 이 방법도 개인별 공명구조의 차이에 기인한 변동이 심하므로 그 효용의 관계가 있었다. 저자들은 이러한 개인별 차이를 줄이기 위해 정상 성인 남자 20명에서 한국 모음 /a/, /i/, /u/, /e/, /o/에 대하여 각각 정상 발음, 인공적으로 일으킨 비폐색, 비개방음을 음향학적으로 분석하여 보았다. 결과, Formant의 변화를 관찰하였고 비음의 객관적 지표로써 이용 가능성을 알 수 있었다.

• 말소리와 음성과학
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• 제2권4호
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• pp.229-238
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• 2010

This study investigates the differences in acoustic parameters in vowel space across hearing loss, gender and vowels. The parameters include F1, F2, Euclidean Distance between vowels, and vowel triangular area comprised of /i/, /a/ and /u/. For this study, 20 hearing-impaired and normal hearing adults as a control group were asked to read 7 Korean vowels (/a, $\wedge$, o, u, w, i, $\varepsilon$/). Subjects' readings were recorded by NasalView and analyzed by Praat. Results showed that F1 were significantly higher in the hearing impaired group than in the normal hearing group, higher in the female group than in male group, and higher in low vowels than in high vowels. And the means of F2 was significantly higher in the hearing impaired group than in normal hearing group, higher in high vowels than in low vowels, and there was no difference between male and female group. Secondly, Euclidean distance between vowels was significantly shorter in the hearing-impaired group than in the normal group. Finally, acoustic vowel space area was significantly smaller in the hearing-impaired group than in the normal hearing group. The hearing-impaired group showed that front vowels tended to be backed and back vowels to be fronted.