• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.131-138
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• 2014

This paper is on a stereo acoustic echo canceller with the blind signal separation for post processing. The convergence speed of the stereo acoustic echo canceller is deteriorated due to mixing two residual signals which are update signals of each echo canceller. To solve this problem, we are to use the blind signal separation(BSS) method separating the mixed signals after the echo cancellers. The blind signal separation method can extracts the source signals by means of the iterative computations with two input signals. We had verified performances of the proposed acoustic echo canceller for stereo through simulations. The results of simulations show that the acoustic echo canceller for stereo using this algorithm operates stably without divergence in the normal state. And, when the speech signals were inputted, this echo canceller achieved about 2dB higher ERLE with the BSS post processing method than without this method. This stereo echo canceller showed the best performance in the case of inputting the real voice signal.

• Speech Sciences
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• v.8 no.3
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• pp.235-241
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• 2001

The purpose of this study was to determine the correlation between HNR and NNE, EGG HNR and EGG NNE, which are most closely related to noise of voice. Dr. Speech was utilized to obtain acoustic measurements and physiologic measurements, simultaneously. In addition, no normative data of HNR, NNE, EGG HNR, EGG NNE are available in Korean subjects at present. The Pearson correlation coefficient was used to find the correlation between HNR and NNE, EGG HNR and EGG NNE. The results of the study were as follows: First, there was no correlation between HNR and NNE. Second, there was a negative correlation between EGG HNR and EGG NNE. Finally, the mean value of HNR of normal Korean adults was $28.8\pm2.7$ dB, that of NNE -$11.7\pm3.9$ dB, that of EGG HNR $32.9\pm4.6$ dB, and that of EGG NNE $-30.3\pm4.6$ dB.

• Speech Sciences
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• v.8 no.3
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• pp.201-208
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• 2001

The purpose of the study was to examine a method most pertinent to measure subglottic air pressure. Subglottic air pressure and loudness analyses were performed on vowels /a/, /i/ and consonant /p/ in 12 normal subjects using. Aerophone II voice function. The experimental contexts were, therefore, /i:pi:pi:/ and /a:pa:pa:/. The subjects produced the intervocalic /p/ in 4 different situations: 1) /i:pi:pi:/ with voiceless /p/, 2) /i:pi:pi:/ with voiced /p/, 3) /a:pa:pa:/ with voiceless /p/, and 4) /a:pa:pa:/ with voiced /p/. A t-test and a correlation analysis revealed the following results. First, when we measured subglottic air pressure by /i:pi:pi:/, voiceless /p/ was significantly different from voiced /p/. Second, when we measured subglottic air pressure by /a:pa:pa:/, voiceless /p/ was significantly different from voiced /p/. Therefore, it was concluded that voiceless /p/ produced more accurate subglottic air pressure and clinicians needed to have patients produce accurate /p/ when measuring subglottic air pressure using Aerophone II.

• Speech Sciences
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• v.7 no.4
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• pp.83-90
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• 2000

The purpose of this study was to examine some acoustic characteristics in the ear canal. It was assumed that a sound outside the external auditory canal could be different from the sound inside the external auditory canal. The acoustic signals were captured by a probe microphone placed at a distance within 1 cm from the tympanic membrane, and a reference microphone was placed over the upper pinna. Three vowels /a/, /i/, /u/ were recorded from a normal adult male speaker. The parameters such as the formant frequency ($Fl\simF5$) and the peak intensity were measured using a speech analyser, PCquirer. It was found that the entering part of the external auditory canal functions as a narrowing point as to the speech that passes through the free field. Results show that acoustic characteristics were changed for speech discrimination rather than speech perception.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.3 no.1
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• pp.22-28
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• 1989

Laryngostroboscopy is one of the most practical techniques for clinical examination of the larynx. The videostroboscopy provides valuable information concerning the nature of vocal folds' vibration, an immediate image of the presence or absence of pathology, and a permanent record. Additionally, when used by trained observers in conjunction with other instrumentation, it can provide both qualitative and quantitative data on vocal function of both the normal and disordered larynx. The authors examined the 388 patients with voice disorders by videostroboscope. This paper describes the clinical procedure of laryngostroboscopy based on some introductory remarks on laryngeal anatomy and function. And the findings of parameters observed by the stroboscopy is noted for the laryngeal disorders.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.1064-1069
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• 1994

In order to realize the function of human interface of telecommunications whose objective is to interchange useful information among persons, we developed a bone conduction telephone with which hearing impaired persons with conductive or noise-induced hearing loss and presbycusis can communicate with each other without any other additional devices such as hearing aids. The bone conduction telephone we developed has chatacteristics as follows : (i) a hearing impaired person and a normal hearing person can communicate by bone and air conduction hearings, respectively, using only this telephone set because, as its receiver, it uses a bone conduction vibrator with which we can realize such function with the voice coil and damper of a small speaker unit, the vibrating plate, etc., (ii) it has tone control function compensating hearing losses of hearing impaired persons according to their hearing loss/frequency chatacteristics. Using the tone control function together with a received volume control, it has the received volume range of 20dB in loudness rating; and (iii) it has the function of three emergency calls and a bell lamp as the visual display of a received call.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6296-6301
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• 2013

To examine the effects of voice disorders after a laryngeal injuryon the changes in stress, this study examined the effects of the changes observed in laboratory animals and on stress reduction effects, by inducing a laryngeal injury in SD type rats after administering a kudzu leaf extract, which has a sedation effect. For testing, a total of 24 rats comprising the normal group, control group and experimental groups (1 and 2 6 rats in each group) were used, and antioxidant experiments and molecular and chemical tests were conducted by administering a specified amount of kudzu teaorally once a day at a set time, 6 times per week for 5 weeks. The control group appeared to be significantly higher than the normal group (p <0.05), whereas the experimental group showed significant decreases compared to the control group (p <0.05), showing a better result than the normal group. The test results showed that the kudzu leaf extract resulted in significant changes compared to the control group. Overall, the administration of kudzu leaf extract has stress reduction effects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1107-1114
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• 1999

In this paper, we analyze the effect of co-channel interferers coming from other systems with composite log-normal shadowing and Nakagami fading on the capacity of the imperfect power-controlled DS/CDMA cellular system. The analytical results are compared with the results of Prasad and Jansen in which they derive the result under the condition of imperfect power-control of DS/CDMA system and without considering interference. And the outage probability is calculated fro the effect of the log-normal/Nakagami faded inferers on DS/CDMA system using Schwartz and Yeh's method. With the deviation of outage probability, we analyzed the decreases in the capacity of DS/CDMA system with the variation of the paramenters of the imperfect power-control, the fadig index, the processing gain, the power ratio, the voice activity factor, and the number of interferers. Analysis reuslts have shown that the capacity of DS/CDMA system is very sensitive to the imperfect power-control and the number of interferers. It is shown that the DS/CDMA system capacity decreased according to increase of the deviation of the impertect power-control, the increase of the fading, and the increase of interferer number.

• Journal of Digital Convergence
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• v.13 no.12
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• pp.187-192
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• 2015

If the software is developed to analyze the speech disorder, the application of various converged areas will be very high. This paper implements the user-friendly program based on CART(Classification and regression trees) analysis to distinguish between normal and pathological voices utilizing combination of the acoustical and HOS(Higher-order statistics) parameters. It means convergence between medical information and signal processing. Then the acoustical parameters are Jitter(%) and Shimmer(%). The proposed HOS parameters are means and variances of skewness(MOS and VOS) and kurtosis(MOK and VOK). Database consist of 53 normal and 173 pathological voices distributed by Kay Elemetrics. When the acoustical and proposed parameters together are used to generate the decision tree, the average accuracy is 83.11%. Finally, we developed a program with more user-friendly interface and frameworks.

• Phonetics and Speech Sciences
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• v.2 no.4
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• pp.75-82
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• 2010

Many previous studies based on respiratory characteristics of Idiopathic Parkinson's Diseases (IPD) patients have not controlled related factors appropriately. Accordingly, these studies produced discordant results. Furthermore, there is currently a lack of studies that can provide precise explanations on the characteristics of respiration and phonation. This study included a total of 40 subjects: 20 mixed gender de novo IPD patients ranging in age from 50 to 80 (Hoehn & Yahr stage 1~3), and 20 normal subjects with similar matches for age and gender. All participants were controlled based on their gender, age, height, weight, vocal fold function, cognitive abilities, and depression factors. K-MMSE (Korean-Mini Mental State Examination), nVHI-10 (new Voice Handicap Index), and KGDS (Korean Form of Geriatric Depression Scale) were evaluated to select this study subjects. In order to compare respiratory functions between the two groups, FVC, FEV1, and FEV1/FVC were measured using microQuark, a PC-based spirometer. CSL was used by measure MPT and PAS was used to measure MFR. To investigate the characteristics of phonation ability, CSL was used to measure jitter and shimmer, while PAS was used to measure Psub. In order to compare the respiratory function averages and phonation ability between the two groups, statistical analysis was conducted using SPSS (version 12.0). The results of this study showed that most de novo IPD patients were included in the normal average range of respiratory and phonatory ability. But the respiratory and phonatory ability of de novo IPD patients showed lower tendency as compared with the normal group. When the average of respiratory and phonatory ability among the gender was compared, the difference of males was greater than the difference of females.