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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
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Volume & Issues
Volume 24, Issue 8 - Nov 2005
Volume 24, Issue 7 - Oct 2005
Volume 24, Issue 6 - Aug 2005
Volume 24, Issue 5 - Jul 2005
Volume 24, Issue 4 - May 2005
Volume 24, Issue 3 - Apr 2005
Volume 24, Issue 2 - Feb 2005
Volume 24, Issue 1 - Jan 2005
Selecting the target year
A Subband Structured Digital Hearing Aid Design for Compensating Sensorineural Hearing Loss
Park Jo-Dong ; Choi Hun ; Bae Hveon-Deok ;
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 238~247
In this Paper. we Presents subband design techniques of a compensating filter and adaptive feedback canceller for the digital hearing aid. The sensorineural hearing loss has a hearing threshold that shows a nonlinear characteristic in frequency domain. and its compensation suffers from an echo that produced by an undesired time varying feedback path. Therefore. the digital hearing aid requires the compensator that can adjust gains nonlinearly in frequency bands and eliminate the echo rapidly In the Proposed digital hearing aid. the compensating filter is designed by the adaptive system identification method in subband structure, and the adaptive feedback canceller is designed by the subband affine projection algorithm. The designed compensation filter can control the nonlinear gain in each subband respectively, therefore precise compensation is possible. And the feedback canceller using the subband adaptive filter achieves fast convergence rate. The Performances of the Proposed method are verified by computer simulations as comparing with the behaviors of the previous trials.
Design of Wideband Speech Coder Using the MLT Residual Signal
Oh Yeon-Seon ; Shin Jae-Hyun ; Lee In-Sung ;
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 248~254
In this Paper, the structure of a split bandwidth wideband speech coder and its highband coder for tone qualify elevation are Proposed. The lowband and highband by the split bandwidth method are encoded independently applying the G.729E and MLT (Modulated Lapped Transform) residual model. In the highband structure which is encoded by low bit rate of 4kbps, the MLT residual signals are distinguished to voice and unvoice signal . The voice signals are applied to MLT peak picking method by lowband pitch period. Because transformed MLT residual signals are represented by periodic signal that have periodic peak. The unvoice signals are applied to MLT which linear prediction spectral response is added and do vector quantization. Performance for proposed 15.8kbps wideband speech coder was verified through subjective listening test.
Experiments on Extraction of Non-Parametric Warping Functions for Speaker Normalization
Shin, Ok-Keun ;
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 255~261
In this paper. experiments are conducted to extract a set of non-Parametric warping functions to examine the characteristics of the warping among speakers' utterances. For this Purpose. we made use of MFCC and LP spectra of vowels in choosing reference spectrum of each vowel as well as representative spectra of each speaker. These spectra are compared by DTW to give the warping functions of each speaker. The set of warping functions are then defined by clustering the warping functions of all the speakers. Noting that male and female warping functions have shapes similar to Piecewise linear function and Power function respectively, a new hybrid set of warping functions is defined. The effectiveness of the extracted warping functions are evaluated by conducting phone level recognition experiments, and improvements in accuracy rate are observed in both warping functions.
Entropy-Constrained Temporal Decomposition
Lee Ki-Seung ;
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 262~270
In this paper, a new temporal decomposition method is proposed. where not oniy distortion but also entropy are involved in segmentation. The interpolation functions and the target feature vectors are determined by a dynamic Programing technique. where both distortion and entropy are simultaneously minimized. The interpolation functions are built by using a training speech corpus. An iterative method. where segmentation and estimation are iteratively performed. finds the locally optimum Points in the sense of minimizing both distortion and entropy. Simulation results -3how that in terms of both distortion and entropy. the Proposed temporal decomposition method Produced superior results to the conventional split vector-quantization method which is widely employed in the current speech coding methods. According to the results from the subjective listening test, the Proposed method reveals superior Performance in terms of qualify. comparing to the Previous vector quantization method.
An Electromagnetic Shock Wave Generator Employing a Solenoid Coil for Extracorporeal Shock Wave Therapy: Construction and Acoustical Properties
Choi Min Joo ; Lee Jong Soo ; Kang Gwan Suk ; Paeng Dong Guk ; Lee Yoon Joon ; Cho Chu Hyun ; Rim Geun Hie ;
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 271~281
An electromagnetic type shock wave generator suitable for extracorporeal shock wave therapy has been constructed by employing a solenoid coil. The Property of the shock waves produced by the shock wave generator was evaluated using a needle hydrophone. It was shown that, as the capacitor discharging voltage increased from 8 to 18 kV, the Positive Peak Pressure (P+) of the shock wave increased non-linearly from 10 to 77 Wa. In contrast. the negative peak Pressure (f) varied between -3.2 and -6.8 MPa. had its absolute maximum of -6.9 ma at 14 kV The peak amplitudes P+ measured repeatedly under the same voltage setting varied within
from mean values and this is very small compared to about
for electrohydraulic type shock wave generators. It could be observed, from the hydrophone signal recorded over 1 ms. several sequential acoustic impulses representing bubble collapses. namely. acoustic cavitation. induced by the shock wave. A technique based on wavelet transformation was used to accurately measure the time delay between the 1st and 2nd collapse known to be closely related to the shock strength. It was observed that the measured time delay increased almost linearly from 120 to
with the shock wave Pressure P+ increasing from 10 to 77 MPa.
Wave Generation and Its Effect on Lesion Detection in Sonoelastography: Theory and Simulation Study
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 282~293
Sonoelastography is an ultrasound-based technique that visualizes the elastic properties of soft tissues by measuring the tissue motion generated by an externally applied vibration. In this paper. the characteristics of wave generation in soft tissues due to an acoustic vibrator are studied. The effects of modal patterns on the detectability of lesions such as tumors in senoelastography are also investigated These are accomplished by analyzing the vibration patterns calculated using theoretical equations and finite element methods in halt space, infinite plate. and finite-sized tissue. A finite-width source generates shear waves with large amplitude Propagating in specific directions. and the generation characteristics depend both on the width and frequency of the vibrator. as well as the distance from it. It is shown in a finite-sized tissue that the lesion detection in displacement images is quit dependent on the modal patterns inside tissue. In contrast it Is also found that the lesion detectability in strain images is less dependent on the modal Patterns and is much better than that in displacement images.
Multiple Target Position Tracking Algorithm for Linear Array in the Near Field
Hwang Soo-Bok ; Kim Jin-Seok ; Kim Hyun-Sik ; Park Myung-Ho ; Nam Ki-Gon ;
The Journal of the Acoustical Society of Korea, volume 24, issue 5, 2005, Pages 294~300
Generally, traditional approaches to track the target position are to estimate ranges and bearings by 2-D MUSIC (MUltiple 519na1 Classification) method. and to associate estimates of 2-D MUSIC made at different time points with the right targets by JPDA (Joint Probabilistic Data Association) filter in the near field. However, the disadvantages of these approaches are that these have the data association Problem in tracking multiple targets. and that these require the heavy computational load in estimating a 2-D range/bearing spectrum. In case multiple targets are adjacent. the tracking performance degrades seriously because the estimate of each target's Position has a large error. In this paper, we proposed a new tracking algorithm using Position innovations extracted from the senor output covariance matrix in the near field. The proposed algorithm is demonstrated by the computer simulations dealing with the tracking of multiple closing and crossing targets.