Simulink를 이용한 음원모델 시뮬레이터 구현

조철우(Jo Cheolwoo),김재희(Kim Jaehee) 한국음성학회 2011 말소리와 음성과학 Vol.3 No.2

In this paper, details of the design and implementation of a voice source simulator using Simulink and Matlab are discussed. This simulator is an implementation by model-based design concept. Voice sources can be analyzed and manipulated through various factors by choosing options from GUI input and selecting pre-defined blocks or user created ones. This kind of simulation tool can simplify the procedure of analyzing speech signals for various purposes such as voice quality analysis, pathological voice analysis, and speech coding. Also, basic analysis functions are supported to compare the original signal and the manipulated ones.

음성의 준주기적 현상 분석 및 구현에 관한 연구

조철우(Jo, Cheolwoo) 한국음성학회 2016 말소리와 음성과학 Vol.8 No.4

The purpose of this work is to analyze and synthesize the pseudo-periodicity of voice using a source model. A speech signal has periodic characteristics; however, it is not completely periodic. While periodicity contributes significantly to the production of prosody, emotional status, etc., pseudo-periodicity contributes to the distinctions between normal and abnormal status, the naturalness of normal speech, etc. Measurement of pseudo-periodicity is typically performed through parameters such as jitter and shimmer. For studying the pseudo-periodic nature of voice in a controlled environment, through collected natural voice, we can only observe the distributions of the parameters, which are limited by the size of collected data. If we can generate voice samples in a controlled manner, experiments that are more diverse can be conducted. In this study, the probability distributions of vowel pitch variation are obtained from the speech signal. Based on the probability distribution of vocal folds, pulses with a designated jitter value are synthesized. Then, the target and re-analyzed jitter values are compared to check the validity of the method. It was found that the jitter synthesis method is useful for normal voice synthesis.

음성신호의 Jitter 성분의 장시간 변화에 관한 통계적 분석

조철우(Cheolwoo Jo) 한국음성학회 2020 말소리와 음성과학 Vol.12 No.4

본 연구에서는 연속음성에서의 장시간 jitter 성분 측정 방법에 대해 고찰하였다. 기존의 jitter측정방법으로는 지속발성한 모음을 대상으로 변동성을 측정하는 방법을 주로 사용하여왔다. 문장음성 등 연속음성의 경우는 문장에 따른 운율정보의 영향으로 기존의 측정법으로는 왜곡이 발생하게 된다. 이에 연속 발성에 대해 운율정보의 피치 변동을 상쇄시키는 방법을 제안하고자 한다. 피치 변동을 제거하는 방법으로는 분석구간내에서의 피치 변동을 다항식 보간법에 의해 변동 경향을 대표하는 곡선을 구하고 그 곡선을 기준으로 변이를 제거하였다. 이후 변이가 제거된 피치의 궤적으로부터 jitter를 측정하는 방법을 적용하여 피치 주파수의 변동성을 측정하고 기존의 지속모음에 의한 측정 방법과 비교하였다. 제안한 방법의 효용성 측정을 위해 Kay Pentax MEEI DB의 음성 표본을 사용하였다. 통계분석 결과 제안된 방법에 의해 연속음성으로부터 측정한 jitter 값은 동일 화자의 지속모음으로부터 측정한 파라미터 값과 유사한 변동성을 보여 주었다. In this study, a method for measuring the jitter component in continuous speech is presented. In the conventional jitter measurement method, pitch variabilities are commonly measured from the sustained vowels. In the case of continuous speech, such as a spoken sentence, distortion occurs with the existing measurement method owing to the influence of prosody information according to the sentence. Therefore, we propose a method to reduce the pitch fluctuations of prosody information in continuous speech. To remove this pitch fluctuation component, a curve representing the fluctuation is obtained via polynomial interpolation for the pitch track in the analysis interval, and the shift is removed according to the curve. Subsequently, the variability of the pitch frequency is obtained by a method of measuring jitter from the trajectory of the pitch from which the shift is removed. To measure the effects of the proposed method, parameter values before and after the operations are compared using samples from the Kay Pentax MEEI database. The statistical analysis of the experimental results showed that jitter components from the continuous speech can be measured effectively by proposed method and the values are comparable to the parameters of sustained vowel from the same speaker.

포만트 정보의 동적 변화특성 조사에 관한 연구

조철우(Jo, Cheolwoo) 한국음성학회 2015 말소리와 음성과학 Vol.7 No.2

This study reports on the effective way of displaying dynamic formant information on F1-F2 space. Conventional ways of F1-F2 space (different name of vowel triangle or vowel rectangle) have been used for investigating vowel characteristics of a speaker or a language based on statistics of the F1 and F2 values, which were computed by spectral envelope search method. Those methods were dealing mainly with the static information of the formants, not the changes of the formant values (i.e. dynamic information). So a better way of investigating dynamic informations from the formant values of speech signal is suggested so that more convenient and detailed investigation of the dynamic changes can be achieved on F1-F2 space. Suggested method used visualization of static and dynamic information in overlapped way to be able to observe the change of the formant information easily. Finally some examples of the implemented display on some cases of the continuous vowels are shown to prove the usefulness of suggested method.

한국어 합성음 평가 가이드라인 시안

조철우(Cheolwoo Jo),이상호(Sangho Lee),김수진(Sujin Kim) 한국정보과학회 영남지부 2005 한국정보과학회 영남지부 학술발표논문집 Vol.13 No.1

This paper suggests some guidelines on evaluating Korean text-to-speech systems in various aspects. Guidelines are suggested in terms of text analysis, intelligibility test and naturalness test and also in terms of generalities and specialties.

이공계 글쓰기 교육의 팀티칭 사례 연구

남경완(Kyoung-Woan Nam),조철우(Cheolwoo Jo) 한국공학교육학회 2012 공학교육연구 Vol.15 No.1

Communication skills, such as writing documents and presenting technical details, are thought to be essential for modern engineers. Engineering students usually have less interest in writing and presentation than their humanities student counterparts and their concerns are different, too. So it is necessary to teach them in a different way which is suited to them. However, teaching such subjects has been a tricky problem for educators in terms of teaching methods. Also, to teach writing and presentation effectively for engineering students, collaboration between the faculties of different disciplines is necessary because each discipline has its own specific domain knowledge and approaches. But many unsolved problems exist with regard to how to deal with the technical and administrative aspects, and so on. This paper introduces one case in the education of technical writing and presentation, which is a collaboration between an engineering faculty and a faculty of literature. The literature faculty conducts basic education and training for writing skills, while the engineering faculty teaches the technical aspects of documentation, as well as presentation skills. The focus is placed on topics such as self-introduction, searching technical literature and materials, describing and explaining things and presentation practice, etc. During the class there is cooperation in each topic domain, while the faculties collaborate in teaching and evaluation.

음원 파라미터 모델과 인공신경망을 이용한 음성장애 검출

파벨 시틸(Pavel Chytil),조철우(Cheolwoo Jo),미샤 파벨(Misha Pavel) 한국음성학회 2008 음성과학 Vol.15 No.2

There is a number of clinical conditions that affect directly or indirectly the physical properties of the vocal folds and thereby the pressure waveforms of elicited sounds. If the relationships between the clinical conditions and the voice quality are sufficiently reliable, it should be possible to detect these diseases or disorders. The focus of this paper is to determine the set of features and their values that would characterize the speaker’s state of vocal folds. To the extent that these features can capture the anatomical, physiological, and neurological aspects of the speaker they can be potentially used to mediate an unobtrusive approach to diagnosis. We will show a new approach to this problem supported with results obtained from two disordered voice corpora.

기식 등급에 따른 CPP (Cepstral Peak Prominence) 분석 비교

강영애(Kang, Youngae),구본석(Koo, Bonseok),조철우(Jo, Cheolwoo) 한국음성학회 2015 말소리와 음성과학 Vol.7 No.1

The aim of this study is to synthesize pathological breathy voice and to make a cepstral peak prominence (CPP) table following breathiness ranks by cepstral analysis to supplement reliability of the perceptual auditory judgment task. KlattGrid synthesizer included in Praat was used. Synthesis parameters consist of two groups, i.e., constants and variables. Constant parameters are pitch, amplitude, flutter, open phase, oral formant and bandwidth. Variable parameters are breathiness (BR), aspiration amplitude (AH), and spectral tilt (TL). Five hundred sixty samples of synthetic breathy vowel /a/ for male were created. Three raters participated in ranking of the breathiness. 217 were proved to be inadequate samples from perceptual judgment and cepstral analysis. Finally, 343 samples were selected. These CPP values and other related parameters from cepstral analysis are classified under four breathiness ranks (B0~B3). The mean and standard deviation of CPP is 16.10±1.15 dB(B0), 13.68±1.34 dB(B1), 10.97±1.41 dB(B2), and 3.03±4.07 dB(B3). The value of CPP decreases toward the severe group of breathiness because there is a lot of noise and a small quantity of harmonics.

뇌졸중 환자 대상 흡인 음성의 음향변수 변동

강영애(Kang, Young Ae),지성주(Jee, Sung Ju),구본석(Koo, Bon Seok),조철우(Jo, Cheolwoo) 한국음성학회 2017 말소리와 음성과학 Vol.9 No.3

The present study aimed to investigate the changes of acoustic parameters of the aspirated voice in stroke patients. The eighty-eight subjects diagnosed with cerebro-vascular accident were divided into 32 penetration/aspiration (P/A) and 56 Non-P/A groups according to the videofluroscopic swallowing study (VFSS) results, and 26 control subjects participated. All subjects preformed VFSS and vowel /a/ was recorded three times pre- and post VFSS. Since the variation in the acoustic parameters within a single phonation has been observed, we proposed a delta formula for the acoustic parameters which can reflect the temporal changes of the each parameter in an utterance. We measured from the voice data eight acoustic parameters: fundamental frequency (F0), standard deviation of F0 (F0_SD), Jitter, relative average perturbation (RAP), Shimmer, amplitude perturbation quotient (APQ), harmonic to noise ration (HNR), noise to harmonic ratio (NHR). Then we found parameters which show the meaningful biggest temporal change in an utterance using the suggested delta parameter. Among them, the deltas of shimmer and APQ were significantly different pre- and post VFSS. These deltas of the P/A and the control group were increased after VFSS, while those of the Non-P/A group was descended. The variation patterns of the P/A and the control group were similar but the change width of the P/A group was larger. The large variations in an aspirated phonation of the P/A group are thought to be caused by irregular changes in air resistance due to residual food on the vocal cords.