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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 32, Issue 6 - Nov 2013
Volume 32, Issue 5 - Sep 2013
Volume 32, Issue 4 - Jul 2013
Volume 32, Issue 3 - May 2013
Volume 32, Issue 2 - Mar 2013
Volume 32, Issue 1 - Jan 2013
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Time Domain Prediction and Analysis of Low Frequency Noise from Wind Turbine using Hybrid Computational Aeroacoustics (CAA) Method
Lee, Gwang-Se ; Cheong, Cheolung ; Kim, Hyung-Taek ; Joo, Won-Ho ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 369~376
DOI : 10.7776/ASK.2013.32.5.369
Using Lowson's acoustic analogy, low frequency noise of a wind turbine (WT) is predicted in time domain and the noise sources contributing to the low frequency noise is analyzed. To compute averaged pressure distribution on blades of the WT as noise source, XFOIL is utilized. The blade source domain is divided into several segments along the span direction to compute force exerted on air surrounding the blade segments, which is used as input for noise prediction. The noise sources are decomposed into three terms of force fluctuation, acceleration and velocity terms and are analyzed to investigate each spectral contribution. Finally, predicted spectra are compared with measured low frequency noise spectrum of a wind turbine in operation. It is found that the force fluctuation component contributes strongly in low frequency range with increasing wind speed.
Performance of COFDM in Underwater Acoustic Channel with Frequency Selective Fading
Seo, Chulwon ; Park, Jihyun ; Park, Kyu-Chil ; Yoon, Jong Rak ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 377~384
DOI : 10.7776/ASK.2013.32.5.377
In this paper, performance of COFDM (Coded Orthogonal Frequency Division Multiplexing) which is OFDM with a forward error correction code, is studied in frequency selective fading underwater acoustic communication channel. The OFDM is a multiplexing technique resistant to frequency selective multipath channel. In OFDM, a broadband information signal is transformed into several narrow band signals and transmits narrow band signals whose bandwidths are less than the channel coherence bandwidth. However, its performance is degraded in a specific narrow band signal due to its deep fading by multipath. To mitigate this degradation, COFDM which is OFDM with convolution code as a forward error correction code, is evaluated. The performance of COFDM is found to be better than that of OFDM in multipath channel.
Analysis of Formula 1 Sound by Doppler Effect
Lee, Chang-Young ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 385~392
DOI : 10.7776/ASK.2013.32.5.385
The sound generated from the formula 1 (F1) machine is characteristic in that the frequency felt by the listener changes drastically by the Doppler effect as the machine bypasses him. In textbooks, longitudinal Doppler effect is usually described. In this paper, we consider a more general case where the listener is away from the rectilinear path of the machine's motion. As the machine bypasses the listener, in this case, the frequency drops not abruptly but gradually, the temporal width for the frequency drop depending on the machine's speed. The frequency shift felt by the listener is analyzed as functions of time and/or machine location in our study. The machine's speed is estimated from the frequency analysis of an actual F1 sound.
Design and Fabrication of a 2D Array Ultrasonic Transducer
Lee, Wonseok ; Woo, Jeongdong ; Roh, Yongrae ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 393~401
DOI : 10.7776/ASK.2013.32.5.393
In this paper, a
channel 2D array ultrasonic transducer with piezoelectric single crystals was designed, fabricated, and evaluated. Structure of the transducer was chosen to facilitate the electric connection on the planar array, and then components were fabricated in accordance with the structure. Detailed structure of the transducer was designed through finite element analyses. In order to improve the performance of the transducer, the crosstalk between adjacent elements was reduced through the control of kerf width and material, and the target frequency bandwidth was achieved through optimal design of the thickness of the single crystal and matching layers. After fabricating a prototype of the transducer according to the design and measuring its characteristics, the results were compared with those of finite element analyses to evaluate the performance of the developed transducer.
An Analysis of the Sound Propagation between Rooms with Different Mediums
Kim, Hyun-Sil ; Kim, Jae-Seung ; Lee, Seong-Hyun ; Seo, Yun-Ho ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 402~407
DOI : 10.7776/ASK.2013.32.5.402
In this paper, an analysis of sound propagation between two rooms with different mediums is discussed. Statistical energy analysis (SEA) is used to consider energy equilibrium among subsystems associated with the sound pressure levels in two rooms and the vibration level of the wall between rooms. Effect of the sound radiation from the structure-borne noise of the wall on sound pressure level of the receiving room is investigated. For a numerical example, sound propagation between engine room and water tank joined by a steel plate whose size is
m, is considered. It is found that when the critical frequency of the plate is above the frequency range of interest, the sound pressure level in the water tank is dominated by sound transmission through the plate, while sound radiation from the structure-borne noise of the plate is negligible except low frequency range below 63 Hz.
Intelligent Adaptive Active Noise Control in Non-stationary Noise Environments
Mu, Xiangbin ; Ko, JinSeok ; Rheem, JaeYeol ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 408~414
DOI : 10.7776/ASK.2013.32.5.408
The famous filtered-x least mean square (FxLMS) algorithm for active noise control (ANC) systems may become unstable in non-stationary noise environment. To solve this problem, Sun's algorithm and Akhtar's algorithm are developed based on modifying the reference signal in update of FxLMS algorithm, but these two algorithms have dissatisfactory stability in dealing with sustaining impulsive noise. In proposed algorithm, probability estimation and zero-crossing rate (ZCR) control are used to improve the stability and performance, at the same time, an optimal parameter selection based on fuzzy system is utilized. Computer simulation results prove the proposed algorithm has faster convergence and better stability in non-stationary noise environment.
Audio Fingerprint Binarization by Minimizing Hinge-Loss Function
Seo, Jin Soo ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 415~422
DOI : 10.7776/ASK.2013.32.5.415
This paper proposes a robust binary audio fingerprinting method by minimizing hinge-loss function. In the proposed method, the type of fingerprints is binary, which is conducive in reducing the size of fingerprint DB. In general, the binarization of features for fingerprinting deteriorates the performance of fingerprinting system, such as robustness and discriminability. Thus it is necessary to minimize such performance loss. Since the similarity between two audio clips is represented by a hinge-like function, we propose a method to derive a binary fingerprinting by minimizing a hinge-loss function. The derived hinge-loss function is minimized by using the minimal loss hashing. Experiments over thousands of songs demonstrate that the identification performance of binary fingerprinting can be improved by minimizing the proposed hinge loss function.
Effects of Hearing Protection Methods and Noise Directions on Bone-Conduction Sensitivity
Han, Woojae ; Yu, Jyaehyoung ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 423~429
DOI : 10.7776/ASK.2013.32.5.423
The present study aimed to find the most sensitive placement of the skull to perceive speech through the bone vibrator in various protection methods while being exposed to noise. Twenty young normal-hearing adults (10 male and 10 female) participated in the study. As stimulus, Korean spondee words were presented via one of five skull locations (i.e., jaw angle, condyle, temple, mastoid, and vertex), while the participants wore one of four protection methods (i.e., ear form, ear plug, ear muff, and ear form and muff together) against white noise in one of four noise directions (i.e., 0, 90, 180, 270 degrees). The results showed: 1) there was a significant difference among the five skull locations with condyle being the most sensitive placement; 2) there was a significant difference among the four protection methods, with the ear form plus ear muff condition (or dual protection) providing the lowest threshold; 3) when exposed to noise from 90 degrees, the significantly lowest threshold was found; 4) there was no significant difference in results by gender. The pattern of results suggests that the communicative condition via the condyle bone conduction and the dual protection of the air conduction under any noise direction might be ideal for preventing noise-induced hearing loss, although further studies should be undertaken in this area.
Perception of Time-altered Sentences and Selective Word Stress by Normal-hearing Listeners
Han, Woojae ; Yu, Jyaehyoung ; Cho, Soojin ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 430~437
DOI : 10.7776/ASK.2013.32.5.430
The present study examined whether sentence perception scores were changed under various conditions of time alteration (compression and/or expansion) and selective word stress in normal hearing listeners. Twenty young normal hearing adults (ten males) were participated. As stimuli, Korean standard-sentence list for adults (KS-SL-A) modified to semantically anomalous sentences was newly recorded by a female speaker. Seven different time-altered conditions (e.g.,
, 0 %) were controlled. To see the effect of selective word stress (i.e., the emphasis of specific syllables in the sentence), all subjects were tested twice 2 weeks apart. The results showed 1) there was significantly different sentence perception scores among the different time-altered conditions, yet only in the 60 % compression condition; 2) there was no significant difference of the sentence perception scores in the effect of stress; however, there was a positive effect of the selective word stress in the sentences consisting of 6 ~ 7 syllables at the 40 % compression condition; 3) there was no significant gender difference. The pattern of results suggests that the combination of time compression and selective word stress is more effective to understand speech, instead of only using time expansion condition. However, further studies should be needed for standardization.
An Enhancement of Japanese Acoustic Model using Korean Speech Database
Lee, Minkyu ; Kim, Sanghun ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 438~445
DOI : 10.7776/ASK.2013.32.5.438
In this paper, we propose an enhancement of Japanese acoustic model which is trained with Korean speech database by using several combination strategies. We describe the strategies for training more than two language combination, which are Cross-Language Transfer, Cross-Language Adaptation, and Data Pooling Approach. We simulated those strategies and found a proper method for our current Japanese database. Existing combination strategies are generally verified for under-resourced Language environments, but when the speech database is not fully under-resourced, those strategies have been confirmed inappropriate. We made tyied-list with only object-language on Data Pooling Approach training process. As the result, we found the ERR of the acoustic model to be 12.8 %.
A Study on the Notation of Jeongganbo Score using Extensible Markup Language (XML)
Lee, Yong Ju ; Choi, Keunwoo ; Park, Tae Jin ; Kang, Kyeongok ;
The Journal of the Acoustical Society of Korea, volume 32, issue 5, 2013, Pages 446~453
DOI : 10.7776/ASK.2013.32.5.446
In this paper, we propose an efficient method to describe and save Jeongganbo score which has various structures and symbols by using XML (Extensible Markup Language). To do this, analysis of Jeongganbo's structures, and classification of symbols for jeongganbo were preformed. Then, Jeongganbo DTD (Document Type Definition) was defined to describe Jeongganbo score in XML document. To verify the proposed method, we produced a Jeongganbo score XML file for real Jeongganbo score according to the proposed Jeongganbo DTD, and then evaluated the produced XML file by using Jeongganbo XML interpreter software which can interpret the Jeongganbo XML file and represent the Jeongganbo score.