• Title/Summary/Keyword: Line spectrum pairs

Search Result 24, Processing Time 0.022 seconds

Efficient vector-scalar quantization of line spectrum parirs (LSP) (효율적인 벡터-스칼라 Line spectrum pairs(LSP) 양자화 방법)

  • 이인성;남승현
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.21 no.2
    • /
    • pp.333-339
    • /
    • 1996
  • In this paper, an effiicent quatization method of line spectrum pairs(LSP) with cascaded structure of vector quantizer and scalar quantizer is proposed. First, input LSP parameters is vector-quantized using a codebook with a moderate number of entries. In the second stage of quantization, the components of residual vector are individution improve the quantizer by the scalar quantizer. The utilization of ordering property and the inclusion of interframe prediction improve the quantizer performance and remove the stability check routine. The new vector-scalar cascaded quantizer using 27 bits/frame shows a transparent quality that an average specytural distortion is 1 dB and the frame proportion with above 2 dB spectral distion is less than 2%.

  • PDF

A Study on the Estimation of Glottal Spectrum Slope Using the LSP (Line Spectrum Pairs) (LSP를 이용한 성문 스펙트럼 기울기 추정에 관한 연구)

  • Min, So-Yeon;Jang, Kyung-A
    • Speech Sciences
    • /
    • v.12 no.4
    • /
    • pp.43-52
    • /
    • 2005
  • The common form of pre-emphasis filter is $H(z)\;=\;1\;- az^{-1}$, where a typically lies between 0.9 and 1.0 in voiced signal. Also, this value reflects the degree of filter and equals R(1)/R(0) in Auto-correlation method. This paper proposes a new flattening algorithm to compensate the weaked high frequency components that occur by vocal cord characteristic. We used interval information of LSP to estimate formant frequency. After obtaining the value of slope and inverse slope using linear interpolation among formant frequency, flattening process is followed. Experimental results show that the proposed algorithm flattened the weaked high frequency components effectively. That is, we could improve the flattened characteristics by using interval information of LSP as flattening factor at the process that compensates weaked high frequency components.

  • PDF

A Study on Measuring the Speaking Rate of Speaking Signal by Using Line Spectrum Pair Coefficients

  • Jang, Kyung-A;Bae, Myung-Jin
    • The Journal of the Acoustical Society of Korea
    • /
    • v.20 no.3E
    • /
    • pp.18-24
    • /
    • 2001
  • Speaking rate represents how many phonemes in speech signal have in limited time. It is various and changeable depending on the speakers and the characters of each phoneme. The preprocessing to remove the effect of variety of speaking rate is necessary before recognizing the speech in the present speech recognition systems. So if it is possible to estimate the speaking rate in advance, the performance of speech recognition can be higher. However, the conventional speech vocoder decides the transmission rate for analyzing the fixed period no regardless of the variety rate of phoneme but if the speaking rate can be estimated in advance, it is very important information of speech to use in speech coding part as well. It increases the quality of sound in vocoder as well as applies the variable transmission rate. In this paper, we propose the method for presenting the speaking rate as parameter in speech vocoder. To estimate the speaking rate, the variety of phoneme is estimated and the Line Spectrum Pairs is used to estimate it. As a result of comparing the speaking rate performance with the proposed algorithm and passivity method worked by eye, error between two methods is 5.38% about fast utterance and 1.78% about slow utterance and the accuracy between two methods is 98% about slow utterance and 94% about fast utterances in 30 dB SNR and 10 dB SNR respectively.

  • PDF

On the Flattening Techniques of Vocal track characteristics by using position information of the LSP (Line Spectrum Pairs) (LSP parameter의 위치정보를 이용한 성도특성 평탄화기법)

  • Kim YoungKyou;MIN SoYeon;BAE MyungJin
    • Proceedings of the Acoustical Society of Korea Conference
    • /
    • spring
    • /
    • pp.171-174
    • /
    • 2002
  • 음성신호는 성문특성으로 인해 고주파 특성이 약화되는 경향이 있다. 이를 보상하기 위해 Pre-emphasis filter를 사용한다. 수식으로 표현하면 y(n)=s(n)-As(n-1) 와 같이 차분방정식으로 나타낼 수 있다. 여기서 A값은 보통 0.9에서 1사이의 값을 주로 사용한다. 그러나 Pre-emphasis filter는 고주파 특성을 보상하는 과정에서 극점과 같이 영점도 왜곡된다. 본 논문에서는 음성특성에 따른 LSP(Line Spectrum Pairs) 분포특성을 이용하여 영점을 보존하고 vocoder 및 coding에 필연적인 고주파 특성 혹은 저주파 특성을 강조한다.

  • PDF

A Study on the Frequency Scaling Methods Using LSP Parameters Distribution Characteristics (LSP 파라미터 분포특성을 이용한 주파수대역 조절법에 관한 연구)

  • 민소연;배명진
    • The Journal of the Acoustical Society of Korea
    • /
    • v.21 no.3
    • /
    • pp.304-309
    • /
    • 2002
  • We propose the computation reduction method of real root method that is mainly used in the CELP (Code Excited Linear Prediction) vocoder. The real root method is that if polynomial equations have the real roots, we are able to find those and transform them into LSP. However, this method takes much time to compute, because the root searching is processed sequentially in frequency region. In this paper, to reduce the computation time of real root, we compare the real root method with two methods. In first method, we use the mal scale of searching frequency region that is linear below 1 kHz and logarithmic above. In second method, The searching frequency region and searching interval are ordered by each coefficient's distribution. In order to compare real root method with proposed methods, we measured the following two. First, we compared the position of transformed LSP (Line Spectrum Pairs) parameters in the proposed methods with these of real root method. Second, we measured how long computation time is reduced. The experimental results of both methods that the searching time was reduced by about 47% in average without the change of LSP parameters.

A Study on the Reduction of LSP(Line Spectrum Pair) Transformation Time in Speech Coder for CDMA Digital Cellular System (이동통신용 음성부호화기에서의 LSP 계산시간 감소에 관한 연구)

  • Min, So-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.8 no.3
    • /
    • pp.563-568
    • /
    • 2007
  • We propose the computation reduction method of real root method that is used in the EVRC(Enhanced Variable Rate Codec) system. The real root method is that if polynomial equations have the real roots, we are able to find those and transform them into LSP. However, this method takes much time to compute, because the root searching is processed sequentially in frequency region. But, the important characteristic of LSP is that most of coefficients are occurred in specific frequency region. So, to reduce the computation time of real root, we used the met scale that is linear below 1kHz and logarithmic above. In order to compare real root method with proposed method, we measured the following two. First, we compared the position of transformed LSP(Line Spectrum Pairs) parameters in the proposed method with these of real root method. Second, we measured how long computation time is reduced. The experimental result is that the searching time was reduced by about 48% in average without the change of LSP parameters.

  • PDF

A Study on Reduction of Computation Time through Adjustment the Frequency Interval Information in the G.723.1 Vocoder (G.723.1 보코더에서 주파수 간격 정보조절을 통한 계산량 감소에 관한 연구)

  • 민소연;김영규;배명진
    • Proceedings of the IEEK Conference
    • /
    • 2002.06d
    • /
    • pp.405-408
    • /
    • 2002
  • LSP(Line Spectrum Pairs) Parameter is used for speech analysis in vocoders or recognizers since it has advantages of constant spectrum sensitivity. low spectrum distortion and easy linear interpolation. However the method of transforming LPC(Linear Predictive Coding) into LSP is so complex that it takes much time to compute. Among conventional methods, the real root method is considerably simpler than others, but nevertheless, it still suffers from its jndeterministic computation time because the root searching is processed sequentially in frequency region. We suggest a method of reducing the LSP transformation time using voice characteristics The proposed method is to apply search order and interval differently according to the distribution of LSP parameters. in comparison with the conventional real root method, the proposed method results in about 46.5% reduction. And, the total computation time is reduce to about 5% in the G.723.1 vocoder.

  • PDF

A Reduction Method of Computational Complexity through Adjustment the Non-Uniform Interval in the Vocoder (음성 부호화기에서 불균등 간격조절을 통한 계산량 단축법)

  • Jun, Woo-Jin
    • Proceedings of the KAIS Fall Conference
    • /
    • 2010.05a
    • /
    • pp.277-280
    • /
    • 2010
  • LSP(Line Spectrum Pairs) Parameter is used for speech analysis in vocoders or recognizers since it has advantages of constant spectrum sensitivity, low spectrum distortion and easy linear interpolation. However the method of transforming LPC(Linear Predictive Coding) into LSP is so complex that it takes much time to compute. Among conventional methods, the real root method is considerably simpler than others, but nevertheless, it still suffers from its indeterministic computation time because the root searching is processed sequentially in frequency region. We suggest a method of reducing the LSP transformation time using voice characteristics.

  • PDF

Coding of LPC Parameters Using the Ordering Property of LSP in the Presence of Channel Errors (전송에러가 있는 채널에서 LSP 순서화특성을 이용한 선형예측계수(LPC)의 양자화 방법)

  • 이인성
    • Proceedings of the Acoustical Society of Korea Conference
    • /
    • 1995.06a
    • /
    • pp.76-80
    • /
    • 1995
  • Differential pulse code modulation 구조의 Line spectrum pairs 양자화기에 높은 차수 LSP 파라미터 값은 낮은 차수 LSP 파라미터 값보다 커야한다는 LSP 파라미터의 순서화 특징을 이용하여 양자화하는 방법을 제시한다. 31 비트/프레임에서 1 dB 이하의 스펙트럴 왜곡을 갖는 명료한 음질을 보였다. 또한 LSP 주파수의 순서화 특성은 벡터-스칼라 결합 양자화기에 적용하였다. 벡터-스칼라 결합 양자화기에서는 26비트/프레임에서 명료한 음질을 보였다. 새로운 LSP 양자화 방법들은 전송에러 발생시 성능을 시험하고, 전송 에러에 강인하도록 프레임간 예측을 위해 Moving Average 예측기를 사용한다.

  • PDF

A Line Spectrum Frequency Pairs Representation for Spectral Envelop Quantization

  • Park, Youngho;Lee, Won-Cheol;Bae, Myung-Jin
    • Proceedings of the IEEK Conference
    • /
    • 2000.09a
    • /
    • pp.787-790
    • /
    • 2000
  • This paper introduces a new type of representation of the LSPs as a promising alternative used for transmitting the LPC parameters. Major contribution in this paper is that the vocal track information embedded on the spectral envelope can be represented in terms of the reduced number of LSF compared tn the conventional. Hence, it provides a possibility that LPC parameters could be quantized at a reduced bit rate without causing any major spectral distortion. The simulation result illustrates the capability of the proposed LSPs representation as an efficient quantization method via a proper rejection of the redundant pairs of pole and zero along the unit circle.

  • PDF