음성 부호화 음질 측정 방법

서정태 한국교통대학교 2020 한국교통대학교 논문집 Vol.55 No.-

This paper presents a robust speech quality measure method for decoded speech. Speech quality is an important means of estimating performance of decoded speech in which most of the transmitted voice signals are corrupted by background noise. Quality information under varying noise environments has traditionally been determined using subjective tests based on human listener rating schemes such as MOS(Mean Opinion Score) and the tests are quite expensive and highly dependent on the test conditions. As a result, it is required to develop an speech quality measure method that can provide a good estimate of subjective quality using the easily obtained objective measure. There has been few studies on practical applications of the real-time system to the mobile system area and especially any channel distortion problems due to the connected local wire-line. In this paper, we study speech quality measure method. From the experimental results, our measure method showed good performance.

정규 펄스를 이용한 VSELP 음성 부호화기

徐廷泰 충주대학교 산업대학원 1999 大學院論文輯 Vol.1 No.-

VSELP is standard technique of Low Bit Rate Speech Coding.Techniques for improving the performance of VSELP-type speech coders while maintaining reasonable computational complexity are explored and,Enhanced coding algorithm is needed for efficient realization. In this paper, Regular Pulse VSELP speech coding algorithm is proposed.For evaluation of proposed coding method,4.8 kbps Regular Pulse VSELP Encoder is implemented using C language. The simulation result at 4.8 kbps bit-rate,proposed method improve speech quality.

二次 長區間 豫測을 利用한 half-rate 音聲 符號化器

徐廷泰 忠州大學校 1996 한국교통대학교 논문집 Vol.31 No.2

Speech requires a large number of bits to express speech in digital form. It is essential to develop a high-performance speech coding algorithm for low bit rate which uses a limited channel capacity effectively. The researches and developments on the low bit rate speech coder have focused on the quality of synthesized sound. A dominant factor that determines the sound quality is the choice of how to model speech signal and how to estimate relevant parameters. In particular, the quality in half rate is known to depend mainly on pitch information. In this paper, a methods improving performance in low bit rate under 4.8 kbps is proposed which adopts the secondary LTP(Long Term Predictor) on the CELP(Code Excited Linear Predictor)-style speech coder, the most remarkable coding method which provides comparatively good quality in low bit rate. In the conventional CELP-style speech coder, quasi-periodic peak components are still remained after the LTP. The proposed method improves the quality of synthesized sound by eliminating the quasi periodicity effectively. It is done by performing the secondary LTP using the adaptive codebook made by excitation signals of the previous frames is proposed. Computer simulation was set to have the transmission rate of 4.8 kbps, and the performance was compared with that of the conventional band-splitted method and that of the DoD-CELP, known to be the standard speech coding method. The proposed method showed better performance in both subjective and objective measure.

음질평가 방법의 비교평가

徐廷泰 충주대 산업과학기술연구소 1999 産業科學論文集 Vol.7 No.1

This paper represents a speech quality comparator for mobile system. Speech quality is an important means of estimating performance of mobile communication services in which most of the transmitted voice signals are corrupted by background noise as well as channel impairments since accurate quality assessment is directly related to end-user satisfaction and ensures to continue high performance of mobile systems. Quality information under varying noise environments has traditionally been determined using subjective tests based on human listener rating schemes such as Mean Opinion Score (MOS) and objective tests such as SegSNR.

음질 평가 기술 연구

서정태 忠州大學校 2008 한국교통대학교 논문집 Vol.43 No.-

Monitoring of speech quality assessment in emerging heterogeneous networks is of great interest to network operators. The most efficient way to satisfy such a need is through Non-intrusive speech quality assessment. In this paper, we review a low-complexity method for monitoring the speech quality assessment. This paper reviews the development of perceptually excited models for quality assessment of speech transmission and storage systems. The main object is to predict subject mean opinion score(MOS) for non-linear, time invariant distortions such as lossy coders, channel errors or noise reduction, particularly for telecommunication application.

방한(In bound)관광상품 수익성 제고 방안

서정태 한국관광정책학회 2000 觀光政策學硏究 Vol.6 No.2

Korean Government expects to accommodate seven million foreign tourists in 2003, and profit twelve billion US dollars as a result of it. If you look, however, at the readiness of domestic atmosphere, you will realize that the competitiveness of Korean tourism products is deteriorating due to the insufficient lodging, attractive tourist sites, food menu and shopping items. This poor domestic atmosphere prompts us to seek some ways to ameliorate our tourist market conditions. In a way to find a solution, the size of tourism expenditure, shopping costs, favored shopping items, and characteristics of purchase patterns of the three major markets of Japan, America, and China that In-bound foreigners are mostly interested in will be analyzed through literature research and field surveys. Also as a strategy to differentiate tourism products, ways of developing distinctive regional products, of strengthening the incentives, of attracting more international conventions are examined. In addition, as a marketing strategy, methods of attracting foreign tourists to the Ministry of Culture and Tourism-designated regional festivals are studied. Lastly as a strategy to stimulate shopping, the production, distribution, and ways of government support of tourism products are analyzed in order to contribute to improve the profitability of tourism products.

음성 부호화기 다중 펄스 연구

서정태 忠州大學校 2012 한국교통대학교 논문집 Vol.47 No.-

The developments on the low bit rate speech coder have focused on the quality of synthesized sound. The quality in low bit rate is known to depend mainly on pitch information. In this paper, a methods improving performance in low bit rate under 4.8 kbps is proposed which adopts the secondary LTP(Long Term Predictor) on speech coder. In addition, method which differ in the way to construct the prediction signal for LTP are proposed. It divides the excitation signal into frequency bands and constructs it with multi-pulse.

낮은 비트 율 음성부호화기의 코드 북 최적화 연구

서정태 한국교통대학교 2016 한국교통대학교 논문집 Vol.51 No.-

A code-book is a document used for implementing a code. A code-book contains a lookup table for coding and decoding. Low bit rate speech codec is a speech coding method used in mobile environments. It is an analysis-by-synthesis coding technique and belongs to the class of speech coding algorithms known as CELP (Code Excited Linear Prediction). Variations of this codec have been used in several standards, including GSM (Half Rate speech). A major drawback of this speech codec is its system complexity. In this paper, It is studied code-book structure analysis and code-book optimization method

분석/합성 음성 부호화기(VSELP)

徐廷泰 忠州大學校 1998 한국교통대학교 논문집 Vol.33 No.2

In recent years, A good technique of low bit rate speech coder is ABS(Analysis by Synthesis) style coder. This paper describes VSELP(Vector sum Error Linear prediction) speech coder. To demonstrate the performance of the VSELP coder, VSELP coder is quantized with 4.8 kbps and it is compared with conventional CELP(Code Excited Linear Prediction) style coder.

음성 부호화기[V-SELP]장 구간 예측 연구

서정태 한국교통대학교 2014 한국교통대학교 논문집 Vol.49 No.-

Code Excited Linear Prediction(celp) Speech Coders exhibit good performance at data rate as low as 4.8Kbps. The major drawback to CELP type Coders is their large computational burden. The vector sum excited linear prediction speech coder utilizes a codebook with a structure which allows for a very efficient search procedure. the code book is organized with a predefined structure which signifucantly reduces the time required for the optimum code word search. v-selp codec utilizes three excitation sources. The first is from long term predictor state, the scond and third sources are from two v-selp excitation codebook. In this paper the vector sum excited linear prediction speech coder is presented. It utilizes a codebook with a structure that allows for a very efficient search procedure. Other advantages of the v-selp codebook structure are discussed, and specially detailed study of Long-term prediction procedure.