• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.297-298
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• 2010

임의의 위치에 음상을 정위하는 방법으로, 머리전달함수(HRTF : Head Related Transfer Function)을 원음에 convolution 하는 기법이 사용된다. 하지만 더미헤드를 이용하여, 각각의 고도각과 방위각에서 측정된 HRTF는 사용자에 따라 정위감을 저하시킬 수 있다. 또한 좌표로 표현되는 영상과는 달리, 소리는 들려오는 방향을 정확한 좌표로 표현하기가 힘들다. 이에 본 논문은 비개인화된 HRTF를 사용하여 음상을 정위하는 경우의 정위감 개선에 대한 방법을 제안한다. 정위감 개선을 위해 음상을 정위하려는 위치 주변의 HRTF를 그룹화하는 방법에 대해 연구하였으며, 그룹화된 HRTF를 이용하여 정위한 음상의 청감평가를 수행하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.8
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• pp.841-848
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• 2008

Based on the averaged Korean head shapes that are the results of digital Korean project by KISTI and Catholic university, experimental apparatus of head dummies of Korean male and female are developed in order to measure head-related transfer functions(HRTF) by using a reverse engineering and rapid prototyping techniques. For the Korean dummies, HRTFs are measured using the substitution method ever 12kHz frequency bands. At every azimuth angle $15^{\circ}$ HRTFs are measured for elevation angles $-30^{\circ}$, $0^{\circ}$ and $-30^{\circ}$. The measured HRTFs are compared with those of KEMAR(knowles electronic manikin for acoustic research) dummy head, which shows $3{\sim}5\;dB$ difference over $4{\sim}5\;kHz$ kHz frequency band.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.669-673
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• 2008

Based on the averaged Korean head shapes that are the results of digital Korean project by KISTI and Catholic university, experimental apparatus of head dummies of Korean male and female are developed in order to measure head-related transfer functions (HRTF) by using a reverse engineering and rapid prototyping techniques. For the Korean dummies, HRTFs are measured using the substitution method over 12 kHz frequency bands. At every azimuth angle $15^{\circ}$ HRTFs are measured for elevation angles $-30^{\circ}$, $0^{\circ}$, and $30^{\circ}$. The measured HRTFs are compared with those of KEMAR (Knowles Electronic Manikin for Acoustic Research) dummy head, which shows a little different frequency characteristic beyond 2 kHz frequency band.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.572-574
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• 2014

Researches on three-dimensional multimedia has been performed actively in recent years. Virtual sound technology corresponding to virtual image should be provided to implement 3D multimedia with high quality. Head-related transfer function (HRTF) plays a key role in this research area. HRTFs measured in changing azimuth, elevation, and distance for each and every subject is necessary for ideal solution. However, it is practically impossible to measure all subjects' HRTFs, so various HRTF databases have been built by many researchers. Because HRTF displays quite different aspects from subject to subject, HRTF of dummy head has been used for generic usage. However, mannequin's HRTF showed much worse performance comparing with individual case so this solution should be improved. From previous work, standardization of HRTF based on tensor-singular value decomposition method has been proposed. For effective extraction of standard HRTF, three different decomposition methods are compared in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1009-1013
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• 2007

To do a HRTF customization, researchers used a spherical head model for modeling the head block of structural modeling of HRTF, which is the one of the technique for HRTF customization, because of its simplicity. In this paper, an analytic spheroidal HRTF caused by an incident point source will be introduced. Using proposed spheroidal HRTF, near-field HRTF customization can be applicable through a structural modeling of HRTF. To see the necessity of sheroidal head model, comparison of two analytic solutions, which are classical spherical HRTF and proposed spheroidal HRTF, will be shown. On the view point of ITD, optimal head model which matches with the measured ITD of KEMAR HRTF can be obtained. ITD results show that there are only slight differences between spherical and spheroidal head model. Magnitude comparison is made by constructing head model using measured head size. Although magnitude comparison is not studied between optimal models, the results of 24 of 36 subjects are shown that spheroidal head model matches notch frequency pattern of measured HRTF better than those of spherical one, where the sound source is at contralateral position.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.706-707
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.338-339
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• 2009

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.98-103
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• 2001

The binaural auditory system of human has the capability of differentiating the direction and distance of sound sources. This feature is well characterised in terms of the inter-aural intensity difference (IID), the inter-aural time difference (ITD) and/or the spectral shape difference (SSD) arising from the acoustic transfer of a sound source to the outer ears. This paper proposes an effective way of extracting the three sound perception factors (IID, ITD, SSD) from the head-related transfer functions (HRTF's) that depends on the direction and distance of the acoustic source from the listener. It includes the estimation method of the equivalent ITD and 1/3-octave band-based IID factors and their usage to locate a sound source in space. Subjective and objective tests were carried out to examine the effectiveness of the proposed methodology and its applicability to real sound systems. Those experimental results are illustrated in this paper.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.4
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• pp.448-457
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• 2008

A principal components analysis (PCA) of the median-plane head-related impulse responses (HRIRs) in the CIPIC HRTF database reveals that the individual HRIRs in the median plane can be adequately reconstructed by a linear combination of 12 orthonormal basis functions. These basis functions can be used to model arbitrary median-plane HRIRs, which are not included in the process to obtain the basis functions. Memory size can be reduced up to 5-fold depending on the number of HRIRs to be modeled. To clarify whether these basis functions can be used to model other set of arbitrary median plane HRIRs, a numerical error analysis for modeling and a series of subjective listening tests were carried out using the measured and modeled HRIRs. The results showed that the set of individual HRIRs in the median plane, which were measured in our lab using different measurement conditions, techniques, and source positions, can be modeled with reasonable accuracy. All subjects, involved in the subjective listening test, reported not only the accurate vertical perception but also the front-back discrimination with the modeled HRIRs based on 12 basis functions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1035-1044
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• 2010

Head-related transfer function (HRTF) is an acoustic transfer function from a sound source to the ear canal entrance position. HRTFs are very important information in the construction of virtual sound fields. HRTFs also vary for different individuals. In this study, characteristics of HRTF for an average Korean are investigated numerically by comparing with the HRTF for a standard Knowles Electronics Manikin for Acoustic Research (KEMAR). A boundary element (BE) model for an adult Korean is developed using the computerized tomography (CT) data in order to investigate the variation in HRTFs for different individuals. The boundary conditions of the BE model are identified by comparing the numerical results with the experimental results. The numerical model shows that accurate HRTFs can be calculated efficiently over full audible frequency range for individuals.