• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.18-26
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• 1997

There are two types of phonetic study, acoustic and physiologic, for differentiating the three manner categories of Korean stop consonants. On the physiologic studies, there are endoscopic, electromyographic(EMG), electroglottographic(EGG) and aerodynamic studies. In this study, I tried to investigate general features of Korean stops using EGG study for the open quotient of vocal fold and baseline shift during speech, and aerodynamic characteristics for e subglottal air pressure, air flow and glottal resistance at consonants. On the aerodynamic study, the glottalized and aspirated stops may be characterized by e increasing subglottal pressure comparing with lenis stop at consonants. The airflow is largest in the aspirated stops followed by lenis stops and glottalized. The glottal airway resistance (GAR) showed highest in the glottalized followed by the lenis, but lowest in e aspirated during e production of consonants, and showed highest in e aspirated, but low in the glottalized and lenis during the production of vowel. The glottal resistance at consonant showed significant difference among consonants and significant interaction between subject and types of consonant. The glottal resistance at vowel showed significant difference among consonants, and e interaction occured between subject and types of consonant. The electroglottography(EGG) has been used for investigating e functioning of e vocal folds during its vibration. The EGG should be related to the patterns of the vocal fold vibration during phonation in characterizing the temporal patterns of each vibratory cycle. The purpose of this study is to investigate the dynamic change of EGG waveforms during continuous speech. The dynamic changes of EGG waveforms fir the three-way distinction of Korean stops were characterized that the aspirated stop appears to be characterized by largest open quotient and smallest glottal contact area of the vocal folds in e initial portion of vocal fold vibration ; the lenis stop by moderate open quotient and glottal contact area ; but the glottalized stop by smallest open quotient and largest glottal contact area. There may be close relationship between the OQ(open quotient) in the initial voice onset and the glottal width at the time of consonant production, the larger glottal width just before vocal fold vibration results in the smaller OQ of the vocal fold vibration in the initial voice onset. The EGG changes of baseline shift during continuous speech production were characterized by the different patterns for the three types of Korean consonants. The small and less stiffness change of baseline shift was found for the lenis and the glottalized, and the largest and stiffest change was found for the aspirated. On the baseline shift for the initial voice onset, they showed so similar patterns with for the consonant production, larger changed in the aspirated. for the lenis and the glottalized during the initial voice onset, three subjects showed individual difference each other. I suggest at s characteristics were strongly related with articulatory activity of vocal tract for the production of consonant, especially for the aspirated stop. The suspecting factors to affect EGG waveforms are glottal width, vertical laryngeal movement and the intrapharyngeal pressure to neighboring tissue during connected spech. So the EGG may be an useful method to describe laryngeal activity to classify pulsing conditions of the larynx during speech production, and EGG research can be controls for monitoring the vocal tract articulation, although above factors to affect EGG would have played such a potentially role on vocal fold vibratory behavior obtained using consonant production.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.9-11
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• 2004

The vocal folds play an important role to produce glottal pulse which is an essential factor of phonation. There have been some models which implement the vocal folds' dynamics, such as one-mass model, two-mass model, multi-mass model and ribbon model. Among them, this paper uses nonlinear two-mass model, which is simple structure and produces similarly real glottal pulses and vocal folds' vibration, to realize vocal folds digital model. The pattern of movements in vocal folds will be shown in this paper by using vocal folds digital model. It will be verified how initial position of vocal folds. variation of tension and change of lung pressure influences vibration and glottal pulses.

• Journal of Biomedical Engineering Research
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• v.20 no.4
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• pp.427-433
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• 1999

The purpose of the study is to develop an improved pitch extraction method that can be used in a variety of speech applications such as high-puality compression and vocoding, and recognition and synthesis of speech. To do so, we develop a new electroglottograph (EGG) measurement system that is based on the four modulation-demodulation type spot electrodes for detecting the EGG signals. Then, the glottal closure instant(GCI) is determined from the EGG signals on a real-time basis. We can obtain the pitch contour using the information on the GCI. It turns out that the new pitch contour algorithm (PCA) operates more reliably as compared to the conventional speech-only-based algorithm. In addition, we study the speech source models and glottal vibratory patterns for Koreans by measuring and analyzing the diversified vibration patterns of the vocal from the EGG signals.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.24 no.1
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• pp.28-32
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• 2013

Because the human voice is produced through vibration of the vocal cords during the exhalation of airflow, it is important to observe the vibration pattern of the vocal cords in patients complaining of voice changes. However, it is not easy to observe the actual vibration pattern of the vocal cord because it vibrates so fast that it cannot be observed by the naked eye and it is located deep in the throat. Recently, with advances in instruments, including laryngoscopes and video camera systems, the vibration pattern of the vocal cords can now be observed. However, considering that present video camera systems can detect 30-60 images per second and the vocal cord vibrates at 100-200 and 200-300 times per second in men and women, respectively, it is not possible to record the whole mucosal wave of the vocal cord in real time. To overcome this limitation, a stroboscope, which converts fast movements of the vocal cord into slower images, has been developed. Since then, several instruments were developed to examine vocal vibration pattern. However, each instruments have advantages and disadvantages. Therefore, we should know about these things to apply them in patients with voice problem.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.5-11
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• 1997

To set up an objective basis for the evaluation of the stroboscopic findings, video-strobolaryngoscopic images of vocal fold vibration in 5 female and 5 male normal speakers were analyzed using an image analysis computer program called KSIP(Kay Storoboscopy Image Processing, Kay Elemetrics Corp., NJ, USA). Four consecutive vibratory cycles were compared in comfortable, louder, high-pitched /ee/ phonation for every subject. findings mostly replicated earlier studies including glottal chinks which were observed in most female speakers throughout the cycles and clear distinction between female and male speakers in their vibratory patterns as well as intensity and frequency-re-lated differences. However, there were some findings incompatible with those from previous studies which may be attributable to technical problems. This study may provide an objective basis of the stroboscopic findings such as image shape, amplitude, area, and their changes according to frequency and intensity variations. We anticipate that funker study with larger samples ran provide an objective criteria for normal vibratory characteristics of the laryngostro-boscopic findings.

• Speech Sciences
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• v.7 no.3
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• pp.153-165
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• 2000

During the phonation of voiced sounds, instants exist where the glottis is opened or closed, due to the periodic vibration of the vocal cord. When closed, this is called the glottal closure instant(GCI) or epoch.. The correct detection of the GCI is one of the important problems in speech processing for pitch detection, pitch synchronous analysis, and so on. Recently, it has been shown that the local maxima points of the wavelet transformed speech signal correspond to the GCIs of speech signal. In this paper, we investigate the accuracy of Gels estimated from this wavelet transformed speech signal. For this purpose we compare them with the negative peak points of the differentiated EGG signal that represents the actual GCIs of speech signal.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.1
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• pp.16-20
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• 2008

Excising part or all part of a larynx as a cancer operation results in changes that transgress anatomic, physiologic, psychologic, and social priciples. The quality of life of a patient's life after any given cancer surgery usually is regarded as a second-priority consideration after oncologic safety. With laryngeal surgery, excision of malignant disease typically results in change that significantly influence an individual for the duration of his or her life. Nonetheless, with appropriate rehabilitation the surgical side effects can be minimized to allow for an excellent quality of life. Successful conservation surgery for laryngeal cancer requires careful interdependent selection for patients, lesions and procedure. The technical goal is to minimize trauma to uninvolved tissue and to wisely utilized local tissues or tree flap for reconstruction, while insuring for oncologically sound procedure. Rehabilitation should aim to produce a glottal sound source if possible, however voice therapy to promote false vocal fold vibration and arytenoid to epiglottis source of vibration can produce very satisfactory phonatory results.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.5 no.1
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• pp.69-74
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• 1994

Thyroplasty type III provides an effective mean of shortening the vocal fold. It is used primarily fer lowering vocal pitch. The indications for this surgery are the male patients with too high a vocal pitch of long duration which has proven resistant to voice therapy and a type of dysphonia characterized by high pitch and a breathy voice, in which the laryngeal findings include a very narrow glottal chink and a small amplitude of vibration, suggesting a stiff vocal cord. In this study, we have experienced two cases of high pitched voice, one is mutational falsetto and other is high pitched, breathy voice with stiff vocal fold. The results were satisfactorily successful with type III thyroplasty. So we report the cases of type III thyroplasty in patients of dysphonia with high pitched voice.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.71-71
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• 1993

Diplophonia is produced by the voice of two separate tones and produced through quasi-periodic variations in the vocal cord vibration. Diplophonia is generally regarded as a symptom of laryngeal pathology. The difference in the vibratory frequency between the vocal cords can be seen in a tension imbalance and a difference in the level of the vocal folds under the special condition such as incomplete glottal closure. So authors have experienced 19 cases of patient with diplophonia for the unilateral vocal cord paralysis, intracordal cysts and other mass lesions. And we analysed the diplophonic voice with peak variability and noise level for the quasi-periodic waveforms and spectrograms pre-and postoperatively.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2725-2736
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• 1998

In this paper. we present a new pitch determination method for speech analysis. namely VFF(Variable Forgetting Factor) based. by using the WRLS-VFF-VT(Weighted Recursive Least Square-Variable Forgetting Factor-Variable Threshold) algorithm. A proposed method uses VFF to identify the glottal closure points which correspond to the instants of the main excitation pulses for voiced speech. The modified EGG