Go to the main menu
Skip to content
Go to bottom
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 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
Selecting the target year
On the Errors of the Phased Beam Tracing Method for the Room Acoustic Analysis
Jeong, Cheol-Ho ; Ih, Jeong-Guon ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 1~11
To overcome the mid frequency limitation of geometrical acoustic techniques, the phased geometrical method was suggested by introducing the phase information into the sound propagation from the source. By virtue of phase information, the phased tracing method has a definite benefit in taking the interference phenomenon at mid frequencies into account. Still, this analysis technique has suffered from difficulties in dealing with low frequency phenomena, so called, wave nature of sound. At low frequencies, diffraction at corners, edges, and obstacles can cause errors in simulating the transfer function and the impulse response. Due to the use of real valued absorption coefficient, simulated results have shown a discrepancy with measured data. Thus, incorrect phase of the reflection characteristic of a wall should be corrected. In this work, the uniform theory of diffraction was integrated into the phased beam tracing method (PBTM) and the result was compared to the ordinary PBTM. By changing the phase of the reflection coefficient, effects of phase information were investigated. Incorporating such error compensation methods, the acoustic prediction by PBTM can be further extended to low frequency range with improved accuracy in the room acoustic field.
Extraction of Characteristics Corresponding to Bell of Taepyeongso Based on Acoustical Analysis
Pyoun, Joong-Bae ; Cho, Sang-Jin ; Hong, Yeon-Woo ; Chong, Ui-Pil ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 12~17
Taepyeongso was introduced from China during the end of the Goryeo period and was used widely in Daechwita (military processional music), Pungmul-nori (farmers music), Buddhist music, royal ancestral rite music, and Sinawi, the instrumental accompaniment to shaman dances. Now, It has been popular as it is used for pop music and it is easy to learn. In this paper, Taepyeongso was analyzed for electronic Taepyeongso using physical modeling. We extracted resonance properties of Taepyeongso through the analysis of Taepyeongso sound. We analyzed the bell, the bore and the mouthpiece using FFT and LPC curve. As a result, the bell could be represented 2 pole filter and reflection filter between bore and bell.
Lossless Coding of Audio Spectral Coefficients Using Selective Bit-Plane Coding
Yoo, Seung-Kwan ; Park, Ho-Chong ; Oh, Seoung-Jun ; Ahn, Chang-Beom ; Sim, Dong-Gyu ; Beak, Seung-Kwon ; Kang, Kyoung-Ok ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 18~25
In this paper, new lossless coding method of spectral coefficients for audio codec is proposed. Conventional lossless coder uses Huffman coding utilizing the statistical characteristics of spectral coefficients, but does not provide the high coding efficiency due to its simple structure. To solve this limitation, new lossless coding scheme with better performance is proposed that consists of bit-plane transform and run-length coding. In the proposed scheme, the spectral coefficients are first transformed by bit-plane into 1-D bit-stream with better correlative properties, which is then coded intorun-length and is finally Huffman coded. In addition, the coding performance is further increased by applying the proposed bit-plane coding selectively to each group, after the entire frequency is divided into 3 groups. The performance of proposed coding scheme is measured in terms of theoretical number of bits based on the entropy, and shows at most 6% enhancement compared to that of conventional lossless coder used in AAC audio codec.
Implementation of Blind Source Recovery Using the Gini Coefficient
Jeong, Jae-Woong ; Song, Eun-Jung ; Park, Young-Cheol ; Youn, Dae-Hee ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 26~32
UBSS (unde-determined blind source separation) is composed of the stages of BMMR (blind mixing matrix recovery) and BSR (blind source recovery). Generally, these two stages are executed using the sparseness of the observed data, and their performance is influenced by the accuracy of the measure of the sparseness. In this paper, as introducing the measure of the sparseness using the Gini coefficient to BSR stage, we obtained more accurate measure of the sparseness and better performance of BSR than methods using the
-norm, and hyperbolic tangent, which was confirmed via computer simulations.
Estimation of Void Fraction in the Seagrass (Zostera Marina) Bed Using Sound Speed Dispersion
La, Hyoung-Sul ; Na, Jung-Yul ; Lee, Sung-Mi ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 33~39
Void fraction of air bubble in the seagrass bed by photosynthesis was estimated with sound speed dispersion. A field experiment was conducted at Seagrasss bed of which bottom type is sandy mud and 120 kHz CW waveform was transmitted to obtain backscattered signals from seagrass bed. The differences of the arrival time of received signal from seagrass bed were observed between day and night. The diurnal variation of arrival time was caused by sound speed dispersion of air bubble generated by photosynthesis of seagrass.
Matched Field Source Localization and Interference Suppression Using Mode Space Estimation
Kim, Kyung-Seop ; Seong, Woo-Jae ; Pyo, Sang-Woo ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 40~46
Weak target detection and localization in the presence of loud surface ship noise is a critical problem for matched field processing (MFP) in shallow water. For stationary sources, each signal component of received signal can be separated and interference can be suppressed using eigen space analysis schemes. However, source motion, in realistic cases, causes spreading of signal energies in their subspace. In this case, eigenvalues of target and interfere signal components are mixed and hard to be separated with usual phone space eigenvector decomposition (EVD) approaches. Our technique is based on mode space and utilizes the difference in their physical characteristics of surface and submerged sources. Performing EVD for modal cross spectral density matrix, interference components in the mode amplitude subspace can be classified and eliminated. This technique is demonstrated with synthetic data, and results are discussed.
Optimal Search Depth for the Sonar Systems in a Range-Dependent Ocean Environment
Lee, Jae-Hoon ; Kim, Jea-Soo ; Yoo, Jin-Soo ; Byun, Yang-Hun ; Cho, Jung-Hong ;
The Journal of the Acoustical Society of Korea, volume 27, issue 1, 2008, Pages 47~56
In the detection of an underwater target, there exists an optimal search depth for the sonar systems, at which the Probability of Detection is maximized. The optimal search depth is dependent on the depths of the target and sonar, the sound speed profile, and the bathymetry. In this paper, we address this question in range-dependent environments, particularly for the bathymetry with slope and with warm eddy. For range-dependent bathymetry, the typical sound profile in the East Sea of Korea was used. The detection range was greater when the sonar was located in deep water than in shallow water. As for the case of eddy, mesoscale warm eddy was used, and the detection range was greater when looking out of the warm eddy than when looking into the eddy.