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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 26, Issue 8 - Nov 2007
Volume 26, Issue 7 - Oct 2007
Volume 26, Issue 6 - Aug 2007
Volume 26, Issue 5 - Jul 2007
Volume 26, Issue 4 - May 2007
Volume 26, Issue 3 - Apr 2007
Volume 26, Issue 2 - Feb 2007
Volume 26, Issue 1 - Jan 2007
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Delayless MDCT for Scalable Speech Codec
Sung, Ho-Sang ; Park, Ho-Chong ;
The Journal of the Acoustical Society of Korea, volume 26, issue 3, 2007, Pages 102~108
A high-Performance scalable speech codec generally requires a very low-rate first layer and a fine granule second layer, and this codec can be implemented with the harmonic codec and the MDCT-based transform codec for each layer. In this structure, however. each codec requires independent frequency transform and the time delay of each codec is accumulated. resulting in long time delay for the overall codec. In this paper, new MDCT structure in the second layer is Proposed. where MDCT is forced to share the look-ahead region of the first layer in order to prevent the time delay accumulation and the resulting functional error of MDCT is analyzed and removed after IMDCT The Proposed delayless MDCT requires no additional bits and Provides the equivalent coding performance with the reduced time delay, yielding a meaningful enhancement of the overall codec.
Improvement of the TCX Module in AMR-WB+ Codec Using Pyramid VQ
Park, Sang-Kuk ; Park, Jung-Eun ; Baik, Seung-Kweon ; Seo, Jung-Il ; Kang, Sang-Won ;
The Journal of the Acoustical Society of Korea, volume 26, issue 3, 2007, Pages 109~114
In this paper, we Propose a pyramid VQ to quantize the transform coefficients of TCX module for the audio improvement of AMR-WB+ codec. The Proposed pyramid VQ is compared to the
Lattice VQ used in the AMR-WB+ standard codec. demonstrating improvement 4% and 5.7%. respectively, in Mean Squared Error (MSE) and 3.3% and 4.7%. respectively, in Perceptual Evaluation of Audio Quality (PEAQ) by 8-dimensional and 16-dimensional Pyramid VQ.
Analysis of the Relation Between Micro-Speaker with the Back Holes and the Ducted Speaker-System
Rhee, Esther ; Oh, Sei-Jin ;
The Journal of the Acoustical Society of Korea, volume 26, issue 3, 2007, Pages 115~122
In this study, the property and the structure of micro-speaker had been firstly shown to be treated as a ducted speaker-system, which was consisted of the unit and the ducted enclosure. With the decrease of total hole area. the resonance frequency of micro-speaker was decreased due to increasing the stiffness or reducing the compliance. The behavior of resonance frequency relative to the total hole area was exactly agreed with that of the square root of compliance. With decreasing the total hole area. the effective chamber volume was increased, but the reference sound pressure level was exponentially reduced in the low and middle frequency range.
Underwater Transient Signal Classification Using Eigen Decomposition Based on Wigner-Ville Distribution Function
Bae, Keun-Sung ; Hwang, Chan-Sik ; Lee, Hyeong-Uk ; Lim, Tae-Gyun ;
The Journal of the Acoustical Society of Korea, volume 26, issue 3, 2007, Pages 123~128
This Paper Presents new transient signal classification algorithms for underwater transient signals. In general. the ambient noise has small spectral deviation and energy variation. while a transient signal has large fluctuation. Hence to detect the transient signal, we use the spectral deviation and power variation. To classify the detected transient signal. the feature Parameters are obtained by using the Wigner-Ville distribution based eigenvalue decomposition. The correlation is then calculated between the feature vector of the detected signal and all the feature vectors of the reference templates frame-by-frame basis, and the detected transient signal is classified by the frame mapping rate among the class database.
Prewhitening Method for LFM Reverberation by Linear Dechirping
Choi, Byung-Woong ; Kim, Jeong-Soo ; Lee, Kyun-Kyung ;
The Journal of the Acoustical Society of Korea, volume 26, issue 3, 2007, Pages 129~135
In this paper. we propose a prewhitening method for the km reverberation to enhance the target signal. The proposed algorithm uses the dechirping method which inversely compensates the frequency chirp rate of LFM and transforms the LFM reverberation to have stationary frequency property in each data block. Also, using the left and right adjacent beam signals as reference signals. we model frequency response of each data block by AR coefficients. From these coefficients, we implement inverse filter and prewhiten the LFM reverberation of the center beam efficiently.