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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 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
Selecting the target year
An Inquiry Over Rayleigh's Pioneering Experiments for the Detection of Shadow, Reflection, Interference, and Diffraction of Sound
Ku, Ja-Hyon ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 55~60
The shadow, reflection, interference, and diffraction are proper phenomena concerning sound that is a kind of wave. By the late nineteenth century, similar optical phenomena had been detected already but these phenomena concerning sound had not been convincingly detected. It was Rayleigh who succeeded in detecting those phenomena without any reasonable doubt by the virtue of his original instruments and smart experimental settings. Rayleigh could detect the sound shadow by using the corner of a building and erase the shadow by some reflectors. And he constructed some apparatus similar to Young's interference apparatus famous in optics to detect the sonic interference. Furthermore, he first succeeded in illustrating the acoustical effectiveness of Poisson's disk by which optical diffraction had already been well known, and tested the effect of diffraction by spherical obstacles to ascertain that the result coincided with his theory.
The Measurement Algorithm for Microphone's Frequency Character Response Using OATSP
Park, Byoung-Uk ; Kim, Hack-Yoon ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 61~68
The frequency response of a microphone, which indicates the frequency range that a microphone can output within the approved level, is one of the most significant standards used to measure the characteristics of a microphone. At present, conventional methods of measuring the frequency response are complicated and involve the use of expensive equipment. To complement the disadvantages, this paper suggests a new algorithm that can measure the frequency response of a microphone in a simple manner. The algorithm suggested in this paper generates the Optimized Aoshima's Time Stretched Pulse(OATSP) signal from a computer via a standard speaker and measures the impulse response of a microphone by convolution the inverse OATSP signal and the received by the microphone to be measured. Then, the frequency response of the microphone to be measured is calculated using the signals. The performance test for the algorithm suggested in the study was conducted through a comparative analysis of the frequency response data and the measures of frequency response of the microphone measured by the algorithm. It proved that the algorithm is suitable for measuring the frequency response of a microphone, and that despite a few errors they are all within the error tolerance.
Subband Affine Projection Algorithm Using Variable Step Size
Choi, Hun ; Bae, Hyeon-Deok ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 69~74
In signal processing applications with highly correlated input signals, subband affine projection algorithm and step size controlling is a good solution for improving the slow convergence rate and large computational complexity of LMS-type algorithms. This paper proposes a subband affine projection algorithm using a variable step size. The proposed method achieves fast convergence rate and small steady-state error with a small computational complexity by combining the SAP and step size controlling in a subband structure. Experimental results on highly correlated input signal show that the proposed method is superior to the conventional methods.
Voice-Based Gender Identification Employing Support Vector Machines
Lee, Kye-Hwan ; Kang, Sang-Ick ; Kim, Deok-Hwan ; Chang, Joon-Hyuk ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 75~79
We propose an effective voice-based gender identification method using a support vector machine(SVM). The SVM is a binary classification algorithm that classifies two groups by finding the voluntary nonlinear boundary in a feature space and is known to yield high classification performance. In the present work, we compare the identification performance of the SVM with that of a Gaussian mixture model(GMM) using the mel frequency cepstral coefficients(MFCC). A novel means of incorporating a features fusion scheme based on a combination of the MFCC and pitch is proposed with the aim of improving the performance of gender identification using the SVM. Experiment results indicate that the gender identification performance using the SVM is significantly better than that of the GMM. Moreover, the performance is substantially improved when the proposed features fusion technique is applied.
Acoustic Properties of Ultrasonic Transducer Using Piezocomposites
Lee, Sang-Wook ; Ryu, Jeong-Tag ; Nam, Hyo-Duk ; Kim, Yeon-Bo ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 80~86
We have investigated on the development of 2-2 type piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the piezoelectric and acoustic properties of 2-2 type piezocomposites sensor which was fabricated using dice-and-fill technique for the different volume fraction of PZT. The specific acoustic impedance of 2-2 type piezocomposites decreased linearly when PZT volume fraction was decreased. The resonance characteristics measured by an impedance analyzer(HP4194A) were similar to the analysis of finite element method (FEM). The resonance characteristics and the electromechanical coupling factor were the best when the volume fraction PZT was 0.6. It also showed the highest result from the standpoint of sensitivity, bandwidth and ring-down property and so on at the same condition. The specific characteristics show that the 2-2 type piezocomposites turned out to be superior to the ultrasonic sensor composed by single phase PZT.
Real-Time Implementation of Active Classification Using Cumulative Processing
Park, Gyu-Tae ; Bae, Eun-Hyon ; Lee, Kyun-Kyung ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 87~94
In active sonar system, aspect angle and length of a target can be estimated by calculating the cross-correlation between left and right split-beams of a LFM(Linear Frequency Modulated) signal. However, high-resolution performances in bearing and range are required to estimate the information of a remote target. Because a certain higher sampling frequency than the Nyquist sampling frequency is required in this performance, an over-sampling process through interpolation method should be required. However, real-time implementation of split-beam processing with over-sampled split-beam outputs on a COTS(commercial off-the-shelf) DSP platform limits its performance because of given throughput and memory capacity. This paper proposes a cumulative processing algorithm for split-beam processing to solve the problems. The performance of the proposed method was verified through some simulation tests. Also, the proposed method was implemented as a real-time system using an ADSP-TS101.
Development of a Thickness Mode Piezoelectric Oscillator Sensor to Detect Damages in a Structure
Kim, Dong-Young ; Roh, Yong-Rae ;
The Journal of the Acoustical Society of Korea, volume 26, issue 2, 2007, Pages 95~101
This paper presents the feasibilityof a thickness mode piezoelectric oscillator to detect damages in structures. The thickness mode oscillator sensor is composed of an electronic feedback oscillator circuit and a piezoelectric thickness mode vibrator to be attached to a structure of interest. Damage to the structure causes a change in the impedance spectrum of the structure, which results in a corresponding change of a resonant frequency of the structure. The oscillator sensor can instantly detect the frequency change in a very simple manner. Feasibility of the piezoelectric oscillator sensor was verified with a sample aluminum plate where artificial cracks of different lengths and number were imposed in sequence. Validity of the measurement was confirmed through comparison of the experimental data with the results of finite element analyses of a plate with cracks.