Multi-Pulse Based Code Excited Linear Predictive Speech Coder with Fine Granularity Scalability for Tonal Language

Journal of Computer Science

2011

Problem statement: In speech communication, speech coding aims at preserving the speech quality with lower coding bitrate. When considering the communication environment, various types of noises deteriorates the speech quality. The expressive speech with different speaking styles may cause different speech quality with the same coding method. Approach: This research proposed a study of speech compression for noise-corrupted Thai expressive speech by using two coding methods of CS-ACELP and MP-CELP. The speech material included a hundredmale speech utterances and a hundred female speech utterances. Four speaking styles included enjoyable, sad, angry and reading styles. Five sentences of Thai speech were chosen. Three types of noises were included (train, car and air conditioner). Five levels of each type of noise were varied from 0-20 dB. The subjective test of mean opinion score was exploited in the evaluation process. Results: The experimental results showed that CS-ACELP gave the better speech quality than that of MP-CELP at all three bitrates of 6000, 8600-12600 bps. When considering the levels of noise, the 20-dB noise gave the best speech quality, while 0-dB noise gave the worst speech quality. When considering the speech gender, female speech gave the better results than that of male speech. When considering the types of noise, the airconditioner noise gave the best speech quality, while the train noise gave the worst speech quality. Conclusion: From the study, it can be seen that coding methods, types of noise, levels of noise, speech gender influence on the coding speech quality.

Section: Introductionmentioning

confidence: 99%

“…Moreover, to improve speech quality for background noise conditions, the adaptive pulse location restriction method are applied . The speech coder operates at various bitrates ranging from 4-12 kbps utilizing the flexibility in multi-pulse excitation coding (Chomphan, 2010a).…”

Section: Introductionmentioning

confidence: 99%

Speech Compression for Noise-Corrupted Thai Expressive Speech

Journal of Computer Science

2011

“…The study concentrates how the noises affect the fundamental frequency contour of the speech by varying the level of signal-tonoise ratio. It is expected to apply the finding knowledge in further study in advanced research such as speech synthesis and recognition (Chomphan, 2009;Chomphan, 2010a;Chomphan, 2010b;Chomphan, 2010c).…”

Section: Introductionmentioning

confidence: 99%

Effects of Noises on the Analysis of Fundamental Frequency Contours for Thai Speech

Journal of Computer Science

2011

Problem statement:In speech communication, noises from surrounding environments affect the communication quality with various aspects. The received speech quality should be analyzed to see how the important noises reduce the speech quality so that we can eliminate them in an appropriate way. Approach: This study presents a study on the analysis of the noise effects on Thai speech. Four kinds of noises; air conditioner, car, factory and train, are chosen to be simulated in the study. The various levels of signal-to-noise ratios are conducted. The root mean square error between the fundamental frequency contours of the corrupted speech and the clean speech is calculated. Finally, the analysis of the root mean square error in terms of comparisons among genders, the four kinds of noises and various levels of signal-to-noise ratios is performed. Results: In the experiments, 400 speech utterances of male and female are used as speech materials. The average values of root mean square error are calculated. The results show that the fundamental frequency contour of female speech is affected more than that of male speech. Comparing among four kinds of noises, the car noise has the highest influence, while the factory noise has the lowest influence. Moreover, the root mean square error is inversely proportional to the level of signal-to-noise ratio. Conclusion: From the finding, the noises from surrounding environments have affected the speech quality of fundamental frequency contour. This study is the preliminary knowledge to enhance the speech quality for further works such as speech synthesis systems or other speech processing technologies.

“…The MP-CELP coder has been proposed to be a scalable coder. This speech coder employs the multipulse excitation which the number of pulses in fixedentry codebook is selective for bitrate scalability and multiple bitrates functionality according to the MPEG-4 CELP speech coder requirements, (Nomura et al, 1998;Chomphan, 2010b). It should be noted that the MP-CELP coder has been developed from the CS-ACELP coder standardized as 8-kb/s G.729 in 1995.…”

Section: Introductionmentioning

confidence: 99%

“…One of standardization activities is conducted under the project of MPEG-4 (Nomura et al, 1998;Chomphan, 2010b). The MP-CELP coder has been proposed to be a scalable coder.…”

Section: Introductionmentioning

confidence: 99%

Speech Compression of Thai Dialects with Low-Bit-Rate Speech Coders

American Journal of Applied Sciences

2012

Problem statement:In modern speech communication at low bit rate, speech coding deteriorates the characteristics of the coded speech significantly. Considering the dialects in Thai, the coding quality of four main dialects spoken by Thai people residing in four core region including central, north, northeast and south regions has not been studied. Approach: This study presents a comparative study of the coding quality of four main Thai dialects by using different low-bit-rate speech coders including the Conjugate Structure Algebraic Code Excited Linear Predictive (CS-ACELP) coder and the Multi-Pulse based Code Excited Linear Predictive (MP-CELP) coder. The objective and subjective tests have been conducted to evaluate the coding quality of four main dialects. Results: From the experimental results, both tests show that the coding quality of North dialect is highest, meanwhile the coding quality of Northeast dialect is lowest. Moreover, the coding quality of male speech is mostly higher than that of female speech. Conclusion: From the study, it can be obviously seen that the coding quality of all Thai dialects are different.