• The Journal of the Acoustical Society of Korea
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• v.35 no.1
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• pp.35-41
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• 2016

Based on correlation and least square method, a closed-form algorithm for estimating the location of mixed far-field and near-field source is presented using the Uniform Circular Array (UCA). Recently, for a homogeneous circular arrangement case, a correlation based closed-form algorithm is proposed to estimate 2-D angle (azimuth, elevation) and the extended algorithm is proposed to 3-D location (azimuth, elevation, range). These algorithms assume the far-field source or near-field source only. Therefore, for mixed source localization, the proposed algorithm estimates source location with the assumption of far-field source, and then estimates the range to distinguish the far-field from the near-field source. For both cases, numerical experiments have been performed, which confirmed the validity of the proposed algorithm.

• The Journal of the Acoustical Society of Korea
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• v.19 no.2
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• pp.54-60
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• 2000

Acoustic source localization using MUSIC etc. utilizes the propagation model in the medium. A plane wave model is a well-known source model for the identification of distant sources in the SONAR and a monopole source model becomes the one for the identification of rather near range sources. This paper introduces a dipole source model and a tripole source model consisting of one monopole and one dipole source. The simplifying procedures provide the simplified factors rather than the superposition of the relating monopole sources. The simulations show that the tripole model is useful in the general case including pure monopole, pure dipole, or pure quadrupole source identification.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.247-251
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• 2013

In this paper, near-field source localization algorithm is presented using Matrix Pencil in Uniform Linear Array(ULA). Based on the centrosymmetry of the ULA, the proposed algorithm decouples the steering vectors which allow for the bearing estimation using Matrix pencil. With estimated bearing, the range estimation of each source is consequently obtained by defining 1D MUSIC spectrum. Simulation results are presented to validate the performance of the proposed algorithm.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.335-338
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• 2004

효과적인 가상음장 재현을 위한 머리전달함수(Head Related Transfer Function: HRTF) 측정 시도는 1994년에 이루어진 MIT의 Bill Gardner에 의한 KEMAR 머리전달 함수 측정 이후 이미 여러 차례에 걸쳐 이루어졌다. 그러나 대부분의 시도는 음원이 머리중심점에서 1 m 이 후에 위치한 원거리에 국한되었고 음원이 1 m나 그 이내에 위치한 근거리에서의 측정은 스피커에서 반사된 음파가 dummy head 나 피험자의 귀에 다시 들어가는 것을 막기 어려워 시도된바가 적으며 data 도 공개되지 않은 것이 현 실정이다. 음원이 머리중심점에서 1 m 보다 가까운 거리에 있는 경우 머리전달함수의 특성은 고도와 방위뿐만 아니라 거리에도 영향을 받는 것으로 알려져 있으며, 이를 알아보기 위해 무향실에 B&K HATS (Head and Torso Simulator)를 설치하고 단극음원에 가까우며 반사가 적은 스피커를 따로 제작하여 근거리 머리 전달함수를 측정하였고 이를 분석하였다.

• The Journal of the Acoustical Society of Korea
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• v.13 no.3
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• pp.41-50
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• 1994

We studied an inherent error be caused by a measuring acoustic intensity using probe which can measure simultaneously the three-dimensional acoustic intensity. This three-dimensional intensity probe was constructed with four microphones, proposed by Suzuki et al. . In the computer simulation, we analyzed the nearfield measurement error with arbitary direction and each of axis direction on the ideal point source and the plate sound source which have finite size. From the results, in case of point source, we obtained accurate measurement below about 1dB when the distance of measurement was about 2.5 times with the distance among microphones in this probe. And in the case of plate sound source, the nearfield measurement error was decreased as the length of one side became above 0.02m, we obtained accurate measurement below about 1dB when the length of one side is 0.2m. The nearfield measurement error of finite size sound is small to ignore. Therefore this probe is useful to measure nearfield intensity.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.164-170
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• 2014

A single near-field sounde source bearing and ranging method based on a independent doublet array is proposed. In the common case of bearing estimation method, unform linear array or uniform circular array are used. It is constrained retaining aperture because of array structure to estimate the distance of the sound source. Recent using independent doublet array sound source's bearing and distance esmtimation method is proposed by wide aperture. It is limited to the case doublets are located on a straight line. In this paper, we generalize the case and estimate the localization of a sound source in the various array structure. The proposed algorithm was verified performance through simulation.

• The Journal of the Acoustical Society of Korea
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• v.18 no.6
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• pp.31-37
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• 1999

This paper describes the far-field estimation using the near-field measurement data. Measurement in far-field region gives us the acoustical characteristics of the source but in general measurement is made in near-field such as acoustic water tank or anechoic chamber, so far-field acoustical characteristics of the source should be predicted from near-field data. In this case, the number of measurement points in the near field which relates to the accuracy of the predicted field and the amount of data processing, should be optimized. Existing papers say that measurement points is proportional to kL and depends on geometry and directivity of the source. But they do not give us any definite criterion for the required number of measurement points. Boundary Collocation Method which is one of the far-field prediction methods, is analyzed based on Helmholtz integral equation and Green function and it has been found that the number of measurement points is optimized as 0.54kL which is about one half of the existing results.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3
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• pp.166-170
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• 2005

This paper describes the experimental study for the position estimation method of underwater sound source using the Nearfield Acoustic Holography. The result confirms that it can be used in the identification of underwater noise sources. The sound sources in the experimental work consists of 2 spherical projectors and the near-Held sound pressure is measured in the hologram plane. From the cross-power spectra of the measured data, the complex sound pressures on the hologram plane is derived and its spatial transformation gives sound fields in a source region. The obtained sound fields in a source region showed that the position of each sound source and their relative source strength are exactly estimated. In conclusion, this technique can be applied for estimation of each source position and its relative strength contribution for the underwater multiple sound sources.

• The Journal of the Acoustical Society of Korea
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• v.22 no.8
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• pp.660-669
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• 2003

This paper describes a theory to calculate sound source field from the spatial transform of sound field and the measured cross-power spectrum of sound pressure over a hologram plane close to a sound source, Calculating method is proposed to solve sound pressures from cross-power spectrums over a hologram plane, For this, Taylor series for the nonlinear equations is expanded, and it is calculated using Newton-Raphon method, Also, a wave number filter is used to reduce errors that is occurred on the backward propagation, and is performed numerical simulation of the circular piston sound source with infinite baffle in water to verify the proposed theory.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.23-29
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• 2017

A concept of a VSA (Virtual Source Array) is the method for an acoustic spatio-temporal focus at a selected location in the outbound direction with respect to the VSA without the need of a probe source as combines a TRP (Time-Reversal Processing) and time-delay and beam-steering. However, in TRP using the VSA concept, it is limited to the critical angle and the short distances relevant to the VSA. In this paper, the waveguide invariant theory is applied to the VSA concept to refocus the received field at ranges greater other than the critical angle and the short ranges by shifting the focused field. The suggested method is verified via numerical simulation, and the results show that the robust acoustic focusing is achieved on the selected location regardless of the limitation on the conventional VSA concept.