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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of the Acoustical Society of Korea
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Journal DOI :
The Acoustical Society of Korea
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Volume & Issues
Volume 27, Issue 8 - Nov 2008
Volume 27, Issue 7 - Oct 2008
Volume 27, Issue 6 - Aug 2008
Volume 27, Issue 5 - Jul 2008
Volume 27, Issue 4 - May 2008
Volume 27, Issue 3 - Apr 2008
Volume 27, Issue 2 - Feb 2008
Volume 27, Issue 1 - Jan 2008
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Experimental Investigation of Characteristics Change by Kerf-Fill Material between Arrayed Elements of a Piezoelectric Transducer
Kim, Jung-Soon ; Kim, Moo-Joon ; Ha, Kang-Lyeol ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 215~220
The kerfs between arrayed piezoelectric elements in a medical ultrasonic transducer or a piezoelectric composite transducer are generally filled by polymeric materials. The boundary condition of the elements for lateral mode vibration is changed according to the kerf-filling materials, so that the resonance frequency for longitudinal mode of the transducer is also varied. In this study, to investigate the resonance frequency variation for an arrayed transducer experimentally, the piezoelectric vibration elements of
were fabricated and those were linearly arrayed. And, the resonance frequencies were measured for three cases of kerf-filling condition, non-filling and two different kinds of epoxy filling. Conclusively, it is confirmed that the resonant frequency variation shows the similar tendency with the theoretical one for the longitudinal mode.
Performance Analysis of the Array Shape Estimation Methods Based on the Nearfield Signal Modeling
Park, Hee-Young ; Lee, Chung-Yong ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 221~228
To estimate array shape with reference sources in SONAR systems, nearfield signal modeling is required for the reference sources near a towed array. Array shape estimation method based on the nearfield signal modeling generally exploits the spatial covariance matrix of the received reference sources. Among those method, nearfield eigenvector method uses the eigenvector corresponding to the maximum eigenvalue as a steering vector of the reference source. In this paper, we propose a simplified subspace fitting method based on the nearfield signal modeling with spherical wave modeling. Furthermore, we analyze performance of the array shape estimation methods based on the nearfield signal modeling for various environments. The results of the numerical experiments indicate that the simplified subspace fitting method and the nearfield eigenvector method with single reference source shows almost similar performance. Furthermore, the simplified subspace fitting method with 2 reference sources consistently estimates the shape of the array regardless of the incident angle of the reference sources, whereas the nearfield eigenvector method cannot apply for the case of 2 reference sources.
An Assessment on the Sound Quality of the Car Audio System Using the Orthogonal Designs
Doo, Se-Jin ; Choi, Kyung-Mee ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 229~238
Audio tuning improves not only the sound quality of the car audio but also the quality of the completed car itself. However without the subjective assessment on the users' preferences, it is hard to tune the car audio satisfying them. Even though there are lots of factors to be considered to assess the preferences, only a restricted number of factors should be included in the experiment because the total number of experiments increases rapidly as the number of factors in the experiment increases. A large number of factors make it hard to explore the relationship between the sound quality and the sound characteristics and also makes the panels exhausted. In this paper, 8 sound characteristics, each with 2 levels, are considered for the experiment. An orthogonal design of experiment is suggested to reduce the number of experiments from 256 to 16. The analysis of variance is applied to show that Treble is the most significant characteristic of the reproduced sound of the given pop music. Also Deep Bass, SAD, and the interaction between Treble and SAD are found to be significant. For the given classic music, SAD is the only characteristic which turns out to be significant.
Robust Audio Identification Using Spectro-Temporal Subband Centroids
Seo, Jin-Soo ; Lee, Seung-Jae ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 239~243
This paper proposes a new audio identification method based on a combination of the instantaneous and dynamic spectral features of the audio spectrum. Especially we propose the spectro-temporal subband centroids that are easy to compute and effective to summarize the instantaneous and dynamic spectral variations. Experimental results demonstrate that the identification performance can be greatly improved by combining both the spectral and the temporal subband centroids.
Audio-Visual Content Analysis Based Clustering for Unsupervised Debate Indexing
Keum, Ji-Soo ; Lee, Hyon-Soo ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 244~251
In this research, we propose an unsupervised debate indexing method using audio and visual information. The proposed method combines clustering results of speech by BIC and visual by distance function. The combination of audio-visual information reduces the problem of individual use of speech and visual information. Also, an effective content based analysis is possible. We have performed various experiments to evaluate the proposed method according to use of audio-visual information for five types of debate data. From experimental results, we found that the effect of audio-visual integration outperforms individual use of speech and visual information for debate indexing.
Discriminative Weight Training for Gender Identification
Kang, Sang-Ick ; Chang, Joon-Hyuk ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 252~255
In this paper, we apply a discriminative weight training to a support vector machine (SVM) based gender identification. In our approach, the gender decision rule is expressed as the SVM of optimally weighted mel-frequency cepstral coefficients (MFCC) based on a minimum classification error (MCE) method which is different from the previous works in that different weights are assigned to each MFCC filter bank which is considered more realistic. According to the experimental results, the proposed approach is found to be effective for gender identification using SVM.
Speech Enhancement Based on Minima Controlled Recursive Averaging Technique Incorporating Conditional MAP
Kum, Jong-Mo ; Park, Yun-Sik ; Chang, Joon-Hyuk ;
The Journal of the Acoustical Society of Korea, volume 27, issue 5, 2008, Pages 256~261
In this paper, we propose a novel approach to improve the performance of minima controlled recursive averaging (MCRA) which is based on the conditional maximum a posteriori criterion. A crucial component of a practical speech enhancement system is the estimation of the noise power spectrum. One state-of-the-art approach is the minima controlled recursive averaging (MCRA) technique. The noise estimate in the MCRA technique is obtained by averaging past spectral power values based on a smoothing parameter that is adjusted by the signal presence probability in frequency subbands. We improve the MCRA using the speech presence probability which is the a posteriori probability conditioned on both the current observation the speech presence or absence of the previous frame. With the performance criteria of the ITU-T P.862 perceptual evaluation of speech quality (PESQ) and subjective evaluation of speech quality, we show that the proposed algorithm yields better results compared to the conventional MCRA-based scheme.