• Journal of Broadcast Engineering
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• v.11 no.4 s.33
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• pp.448-457
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• 2006

HRTF DB, including the information of the sounds which is arrived to our ears, is generally used to make a 3D sound. But it can decline some three-dimensional effects by the confusion between front and back directions due to the non-individual HRTF depending on each listener. In this paper, we propose a new method to use psychoacoustic theory that reduces the confusion of sound image localization. And we make use of an excitation energy by the sense of hearing. This method is brought HRTF spectrum characteristics into relief to draw out the energy ratio about the bark band. Informal listening tests show that the proposed method improves the front-back sound localization characteristics much better than the conventional methods.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.03a
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• pp.187-191
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• 1999

종래의 입체음향 재생은 3개 이상의 여러대의 스피커를 이용하는 멀티 채널방식의 입체음향이 주류를 이루고 있다. 간혹, 2개의 스피커나 헤드폰을 이용하는 2채널방식으로 재생된 음향을 구현하는 시스템들이 개발되고 있으나 이는 주로 하드웨어를 기반으로 개발되고 있으며, 최근에 소프트웨어만으로 2채널방식의 입체음향을 구현하는 프로그램들이 외국에서 소개되고 있으나, 이들 제품들은 통합된 의미(방향감, 거리감, 공간감)의 입체음향을 구현하는 것이 아니라 잔향을 이용하는 공간감 생성에 국한되거나, 음상정위에 의한 방향감 생성에 국한되어 입체음향의 일부분 만을 생성하는 경우가 대부분이다. 따라서 순수한 소프트웨어만으로 구현된 하나의 프레임워크 내에서 통합된 의미의 2채널 방식의 입체음향을 생성하는 소프트웨어는 전무한 상태이다. 이에 본 논문에서는 GUI를 통해 3차원 공간상의 가상음원의 위치 및 이동 궤적과 가상공간(공간감)을 사용자가 지정하도록 사였으며, 위치 및 이동 정보의 입력은 시스템 정의 방식과 사용자 정의 방식으로 구분하여 각각 음상정위를 수행하도록 하였다. 또한 공간감을 위한 가상공간의 크기도 사용자가 임의로 정의할 수 있다. 입체음향으로 생성할 수 있는 GUI 환경을 제공하며, 저비용으로 효과적인 입체음향 컨텐트를 제작할 수 있도록 함으로써, 게임 및 멀티미디어 컨텐트 제작의 고부가가치화와 입체음향 기술의 산업화에 기여할 것으로 기대된다.

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.32-38
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• 2002

In the AV system, stereophonic system has been studied to produce a realistic sound effect. The width of stereo AV system speakers is narrow, to have the spatial impression of sound effect, widening the sound image is necessary. The direction of sound image depends on the phase delay and the sound pressure level difference between two channels. In this paper, we analyze the relationship between the phase delay and the direction of the sound image relating to the frequency of sound source. Also we experimented to directionally localize the sound image of the pure tone with shifting phases and controling sound pressure love between two channels when the sound is reproduced by two speakers to make a spatial impression of sound effect.

• Speech Sciences
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• v.11 no.4
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• pp.29-42
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• 2004

This paper presents an implementation of real-time speaker localization using audio-visual information. Four channels of microphone signals are processed to detect vertical as well as horizontal speaker positions. At first short-time average magnitude difference function(AMDF) signals are used to determine whether the microphone signals are human voices or not. And then the orientation and distance information of the sound sources can be obtained through interaural time difference. Finally visual information by a camera helps get finer tuning of the angles to speaker. Experimental results of the real-time localization system show that the performance improves to 99.6% compared to the rate of 88.8% when only the audio information is used.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.337-340
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• 2000

입체음향 생성을 위한 기존의 방법은 크게 바이노럴 녹음기법과 머리전달함수(HRTF)를 이용한 바이노럴 합성 기법으로 나눌 수 있다. 기존 2채널 더미헤드를 이용한 바이노럴 녹음기법과 바이노럴 합성기법은 표준 더미헤드를 사용함으로써 청취자 머리와의 오차로 정면 음상 정위의 어려움, "Front-back confusion", 이동 음 음상 정위 어려움 등의 문제로 실제 녹음 현장에서는 거의 사용되지 않고 있다. 본 논문에서 제안한 3채널 더미헤드 기법은 이러한 문제점을 극복할 수 있고, 특히, HRTF 합성 시 기존의 HRTF의 문제점을 극복할 수 있는 새로운 HRTF를 구축할 수 있다. 따라서 바이노럴 합성 기법이 필요한 오락, 시뮬레이터, 음장 가청화 기술(Auralization) 프로그램 등 다양한 분야에서의 적용이 가능하다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.807-810
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• 2000

입체음향 시스템에서 모노음에 방향감을 제어하기 위한 방법으로 FIR 필터 형태의 머리전달함수( HRTF : Head-Related Transfer Function)를 사용한다. 그러나 이때 사용되는 FIR형태의 머리전달함수는 높은 차수를 가지고 있어 실시간 음상정위 처리가 어려운 문제점을 가지고 있다. 본 논문에서는 FIR 형태의 머리전달함수를 ARMA 시스템 인지기법을 이용하여 저차의 IIR필터 형태로 모델링하여 실시간 데이터 처리가 가능하도록 하였다. 본 논문에서 제안하는 ARMA 시스템 인지기법을 이용하게 되면 주어진 고차의 FIR형태의 머리전달함수를 다양한 안정성을 갖는 IIR모델들을 얻을 수 있으며, 이들 중 적절한 스펙트럼오차를 갖는 저차의 IIR모델을 선택 할 수 있다.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.846-860
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• 2011

The binaural auditory system of human has ability to differentiate the direction and the distance of the sound sources by using the information which are inter-aural intensity difference(IID), inter-aural time difference(ITD) and/or the spectral shape difference(SSD). These information is generated from the acoustical transfer of a sound source to pinna, the outer ears. We can create a virtual sound system using the information which is called Head related transfer function(HRTF). However the performance of 3D sound is not always satisfactory because of non-individual characteristics of the HRTF. In this paper, we propose the algorithm that uses human's auditory characteristics for accurate perception. To achieve this, excitation energy of HRTF, global masking threshold and loudness are applied to the proposed algorithm. Informal listening test shows that the proposed method improves the sound localization characteristics much better than conventional methods.

• The Journal of the Acoustical Society of Korea
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• v.30 no.5
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• pp.255-264
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• 2011

The Head Related Transfer Function (HRTF) means a process related to acoustic transmission from 3d space to the listener's ear. In other words, it contains the information that human can perceive locations of sound sources. So, we make virtual 3d sound using HRTF, despite it doesn't actually exist. But, it can deteriorate some three-dimensional effect by the confusion between front and back directions due to the non-individual HRTF depending on each listener. In this paper, we proposed the new algorithm to reduce the confusion of sound image localization using human's acoustic characteristics. The frequency spectrum and global masking threshold of 3d sounds using HRTF are used to calculate the psychoacoustical differences among each directions. And perceptible cues in each critical band are boosted to create effective 3d sound. As a result, we can make the improved 3d sound, and the performances are much better than conventional methods.

• The Journal of the Acoustical Society of Korea
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• v.28 no.6
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• pp.557-565
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• 2009

To perceive the direction and the distance of a sound, we always use a couple of information. Head Related Transfer Function (HRTF) contains the information that sound arrives from a sound source to the ears of the listener, like differences of level, phase and frequency spectrum. For a reproduction system using 2 channels, we apply HRTF to many algorithms which make 3d sound. But it causes a problem to localize a sound source around a certain places which is called the cone-of-confusion. In this paper, we proposed the new algorithm to reduce the confusion of sound image localization. The difference of frequency spectrum and psychoacoustics theory are used to boost the spectral cue among each directions. To confirm the performance of the algorithm, informal listening tests are carried out. As a result, we can make the improved 3d sound in 2 channel system based on a headphone. Also sound quality of improved 3d sound is much better than conventional methods.

• The Journal of the Acoustical Society of Korea
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• v.27 no.4
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• pp.207-214
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• 2008

To create 3D sound, we usually use two methods which are two channels or multichannel sound systems. Because of cost and space problems, we prefer two channel sound system to multi-channel. Using a headphone or two speakers, the most typical method to create 3D sound effects is a technology of head related transfer function (HRTF) which contains the information that sound arrives from a sound source to the ears of the listener. But it causes a problem to localize a sound source around a certain places which is called cone-of-confusion. In this paper, we proposed the new algorithm to reduce the confusion of sound image localization. HRTF grouping and psychoacoustics theory are used to boost the spectral cue with spectrum difference among each directions. Informal listening tests show that the proposed method improves the front-back sound localization characteristics much better than conventional methods.