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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
The Journal of the Acoustical Society of Korea
Journal Basic Information
Journal DOI :
The Acoustical Society of Korea
Editor in Chief :
Volume & Issues
Volume 31, Issue 8 - Nov 2012
Volume 31, Issue 7 - Oct 2012
Volume 31, Issue 6 - Aug 2012
Volume 31, Issue 5 - Jul 2012
Volume 31, Issue 4 - May 2012
Volume 31, Issue 3 - Apr 2012
Volume 31, Issue 2 - Feb 2012
Volume 31, Issue 1 - Jan 2012
Selecting the target year
A Study on Improving Pitch Search for Vocoder
Baek, Geum-Ran ; Bae, Myung-Jin ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 419~426
DOI : 10.7776/ASK.2012.31.7.419
The pitch searching is a vital process in a vocoder. Generally, the method of pitch searching is employed after highlighting the periodicity, where a correlation is identified with the signal by changing the interval of two pulses. When the correlation value reaches the peak, the pitch can be found by the pulse interval because it is the repetition interval with most striking period. However if the identified period happens to be one of half period, double period or triple period, this cannot be considered as the pitch period. Many methods were suggested to solve this problem. An inaccurate pitch could be obtained as well, when there is an interval where signal amplitude is not constant but varies abruptly in the frame. To solve this matter, searching the pitch by dividing a frame into various subframes is adopted, but too much calculation has to be followed while it leads the correct value. This paper suggests an algorithm to resolve these two problems. First, to search the pitch after advance correction of the signal energy level with an estimated overall energy change ratio in the frame before pitch search to reduce half period, double period and triple period is suggested. Second, to vary the number of subframes by predicting the amplitude change rate in the frame by the energy ratio obtained by the above-mentioned method is advised. If these two methods are applied, the pitch searching time can be reduced and the general pitch searching performance can be improved without affecting the sound quality in the synthesized signal.
A Fast Normalized Cross-Correlation Computation for WSOLA-based Speech Time-Scale Modification
Lim, Sangjun ; Kim, Hyung Soon ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 427~434
DOI : 10.7776/ASK.2012.31.7.427
The overlap-add technique based on waveform similarity (WSOLA) method is known to be an efficient high-quality algorithm for time scaling of speech signal. The computational load of WSOLA is concentrated on the repeated normalized cross-correlation (NCC) calculation to evaluate the similarity between two signal waveforms. To reduce the computational complexity of WSOLA, this paper proposes a fast NCC computation method, in which NCC is obtained through pre-calculated sum tables to eliminate redundancy of repeated NCC calculations in the adjacent regions. While the denominator part of NCC has much redundancy irrespective of the time-scale factor, the numerator part of NCC has less redundancy and the amount of redundancy is dependent on both the time-scale factor and optimal shift value, thereby requiring more sophisticated algorithm for fast computation. The simulation results show that the proposed method reduces about 40%, 47% and 52% of the WSOLA execution time for the time-scale compression, 2 and 3 times time-scale expansions, respectively, while maintaining exactly the same speech quality of the conventional WSOLA.
Search of Optimal Contexts for Context-adaptive Coding of Stereo Parameters in Parametric Stereo of Enhanced aacPlus
Pang, Hee-Suk ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 435~440
DOI : 10.7776/ASK.2012.31.7.435
We propose optimal contexts for context-adaptive coding of stereo parameters in parametric stereo (PS) of enhanced aacPlus. For the quantized indexes of stereo parameters, 8 context candidates were proposed based on the index values and their combinations adjacent to a source index in the time-stereo band domain, where the time-stereo band region was further divided into 4 regions based on refresh/non-refresh frames and stereo bands. The optimal contexts for each region were proposed by experiments, which are expected to be used for context-adaptive coding of PS for improved performance.
Sea Trial Results of the Direct Sequence Spread Spectrum Underwater Acoustic Communication in the East Sea
Han, Jeong-Woo ; Kim, Ki-Man ; Yun, Yeong-Jung ; Mun, Hyeon-Uk ; Chun, Seung-Yong ; Son, Kweon ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 441~448
DOI : 10.7776/ASK.2012.31.7.441
Spread spectrum provides the minimized inter-symbol interference, the low probability of intercept and the multiple access capability. This paper presents a direct sequence spread spectrum with carrier/timing recovery and equalizer which compensates the delay spread caused by multipath transmission. When the sea trials were performed in Korean East Sea, the bit error rates of QPSK and direct sequence spread spectrum are
at 3 km source-receiver range, respectively.
A Study on Leak Detection Technique of a Pipe In a Noisy Environment
Yoon, Doo-Byung ; Park, Jin-Ho ; Shin, Sung-Hwan ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 449~460
DOI : 10.7776/ASK.2012.31.7.449
The importance of the leak detection of a buried pipe in a power plant of Korea is being emphasized as the buried pipes of a power plant are more than 20 years old. The objective of this work is to enhance the capability of the leak detection technique in a noisy environment. For this purpose, a modified cross-correlation method that can effectively remove the rotating machinery noise component is suggested. In addition, a method for leak point detection using phase information of cross-spectrum is suggested. The validity of the proposed method is verified by performing an experiment. The experimental result demonstrates that the performance of the cross-correlation method can be enhanced by reducing the periodic noise components due to mechanical equipment.
Prosodic Phrasing and Intonation Patterns in the Speech of Migrant Women from Multicultural Families
Jeong, Jin-Sook ; Lee, Sook-Hyang ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 461~471
DOI : 10.7776/ASK.2012.31.7.461
The purpose of this paper is to provide basic data for development of Korean teaching programs for immigrant women from multicultural families through the acoustic analysis of their prosodic phrasing and intonation pattern. The results showed that immigrant women showed some differences in most of the prosodic characteristics from a Korean women's group: Immigrant women realized the first word of a sentence in an intonational phrase while Korean women did in an accentual phrase. They also haven't yet correctly learned the tone type of the first of an accentual phrase which differs depending on the type of its first segment yet. As a result, they showed many diverse intonation patterns compared to Korean women. Furthermore, the immigrant women's groups showed some differences between them in a few prosodic characteristics. Philippine women, whose residence duration in Korea is relatively longer than that of Vietnamese women, were more similar to Korean women: Vietnamese women read a sentence with a larger number of intonational phrases than Philippine women did. And they realized sentence-final boundary tone of a yes-no question not only in 'H%' but also in 'HL%' while, like Korean women, Philippine women did only in 'H%'.
Design of Low Bits Rate Transform Excitation Wide Band Speech and Audio Coder of Analysis-by-Synthesis Structure
Jang, Sunghoon ; Hong, Kibong ; Lee, Insung ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 472~479
DOI : 10.7776/ASK.2012.31.7.472
This paper is aimed to design 9.2 kbps low bits late transform excitation coder that target to voice and audio signal. To set up low bit rate, we used Band-selection in frequency domain and gain-shape quantization and AbS structure. To decrease lots of calculation from ABS structure, we used each band IDFT and synthesis. And we designed non-transfer band for performance by inserting comfort noise. We propose coder that has low bit rate and similar performance comparing with original 10.4 kbps AMR-WB+ TCX mode.
A Systematic Power Factor Improvement Method for an Electro Acoustic Transducer with Low Coupled Dual Resonances
Lim, Jun-Seok ; Pyeon, Yong-Guk ;
The Journal of the Acoustical Society of Korea, volume 31, issue 7, 2012, Pages 480~486
DOI : 10.7776/ASK.2012.31.7.480
In the design of electro acoustic transducer, power factor improvement circuit is more required rather than impedance matching if the driving power amplifier has little inner resistance. Many research results have been focused on the power matching circuit designing for transferring maximum power in the wideband. There are few results in the designing study on the power factor improvement for the wide band electro acoustic transducer. In this paper, we propose a new design method on the power factor improvement for the wide band electro acoustic transducer. The proposed method consists of two steps, the chebyschev matching method and the constrained optimization, respectively.