• Journal of Advanced Navigation Technology
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• v.14 no.4
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• pp.571-577
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• 2010

Driving aircraft requires extremely complicated and detailed information processing. Pilots perform their tasks by selecting the information relevant to them. In this processing, spatial information presented simultaneously through crossmodal link is advantageous over the one provided in singular sensory mode. In this paper, probability to apply providing visual spatial information along with auditory information to enemy tracking system in aircraft navigation is empirically investigated. The result shows that auditory spatial information, which is virtually created through HRTF is advantageous to visual spatial information alone in attention processing. The findings suggest auditory spatial information along with visual one can be presented through crossmodal link by utilizing stereophonic sound such as HRTF. which is available in the existing simple stereo system.

• The Journal of the Acoustical Society of Korea
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• v.30 no.6
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• pp.337-343
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• 2011

With commencing trial 3D digital broadcasting, the studies on next generation digital broadcasting technology for coming UHDTV era is being actively progressing. In this paper, I propose surround audio formats for next-generation digital TV broadcasting, along with comparative study of major surround audio formats in use or under development. I did comparative study on current major competing surround formats such as Dolby True HD and DTS HD MA, along with NHK proposed 22.2 channel surround format for UHDTV system. Upon this comparative study and our housing situation consideration, I propose lossy compression 3D surround 7.1 channel surround format along with loosless 2.0 and 4.0 hi-fi format as next generation digital TV broadcasting standard. In lieu with this, I also propose transmitting binaural 2 channel audio data as sub-audio. It will give holographic sound experience when properly processed with individual HRTF (Head Related Transfer Function) with headphone. The table for data rate of each proposed audio format is also presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.6
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• pp.581-587
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• 2010

In this study, we investigated the effect of the simplification for low frequency region in Head-Related Transfer Function(HRTF) on the sound localization. For this purpose, HRTF was measured and analyzed. The result in the standard deviation of HRTF showed that the directional dependence of low frequency was smaller than that of high frequency region, which means the possibility of simplification in the low frequency region. Simplification was performed by flattening of the low frequency amplitude characteristics with the insertion of the high-pass filter, whose cutoff frequency is given by boundary frequency. Auditory experiments were performed to evaluate the simplified HRTF. The result showed that direction perception was not influenced by the simplification of the frequency characteristics of HRTF for the error of sound localization. The rate of confusion for the front and back was not affected by the simplification of the frequency characteristics within 1kHz of HRTF. Finally, we made it clear that the sound localization was not affected by the simplification of frequency characteristics of HRTF within 1kHz. The result is expected to be utilized to reduce the size of speech information with no deterioration of the directional characteristics of the speech signal.

• Journal of the Korean Institute of Navigation
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• v.16 no.4
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• pp.55-63
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• 1992

This computer simulation is the basic research for realize a real-time hardware of the reproduction system in original sound field with two loudspeakers based on the OSS(Ortho Stereophonic System) method which was proposed by Hamada of Japan in 1983. Through the computer simulation, presumed the system function of OSS equalizer using HRTF(Head Related Transfer Function), constructed the model of OSS equalizer and , evaluated the modelling OSS equalizer by evaluation formula. The obtained results are summarized as follows : 1) By the modelling OSS equalize operate as inverse filter of HRTF, an input signal reproduced effectively. 2) Known that the real-time hardware of OSS equalizer can be made by the fast convolution between the impulse response of OSS equalizer and input speech signal. 3) Since the system function of OSS equalizer presumed from HRTF, the study on the measuring of HRTF have to proceed.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.632-637
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• 2006

본 논문에서는 가상현실 환경에서 방위각, 고도, 거리 등의 위치 정보를 인지할 수 있는 3 차원 사운드를 생성하기 위한 구조적 머리전달함수(Head-Related Transfer Function, HRTF) 모델을 제안하고 이를 구현한다. 이를 위해 우선 기존에 연구된 방위각과 고도에 관한 head model 과 pinna model 을 근간으로 거리의 변화를 고려하도록 하는 HRTF 모델을 제안한다. 제안된 거리 변화에 따른 HRTF 모델은 거리 차이에 따른 음압의 변화 모델과 근거리에서 사람의 머리에 의해 생기는 shadowing 모델로 구성된다. 본 논문에서는 제안한 모델로 부터 mono 사운드를 방위각, 고도, 거리를 인지할 수 있는 stereo 사운드로 변환하여 생성하는 3 차원 사운드 생성기를 구현하였고, 일반인을 대상으로 거리에 대한 청취 실험을 통하여 제안한 모델의 성능을 측정하였다. 그리고 제안된 모델을 가상현실의 실감모델인 MP3 에 구현하여 그 효과를 입증하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.76-80
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• 2000

본 논문은 입체 음상 정위 시스템에 있어서 청취자의 머리 크기와 음상 정위를 원하는 위치와의 거리에 따른 머리전달함수 (HRTF; Head Related Transfer Function)의 보정 방법에 관한 것이다. 제안된 방법은 먼저 표준 반경에서 표준 머리 크기의 더미 헤드를 이용해 측정된 표준 머리전달함수 데이터베이스로부터 실제의 왼쪽 또는 오른쪽 귀를 기준으로 한 방위각과 고도각을 산출한다. 이렇게 산출된 방위각과 고도각을 기준으로 머리전달함수 데이터베이스의 인덱스를 보정한다. 음상 정위하고자 하는 3차원 공간상의 위치를 입력받게 되면, 입력받은 위치로부터 청취자의 왼쪽 또는 오른쪽 귀를 기준으로 한 방위각과 고도각을 산출한 후에 보정된 머리전달함수 데이터베이스로부터 머리전달함수를 가져와서 입력 모노 신호를 보정된 머리전달함수와 콘볼루션하여 입체음향을 생성하게 된다.제안된 방법에 의해 청취자의 머리 크기 및 거리에 따라 보정된 머리전달함수를 사용함으로써 청취자에게 보다 실감나는 3차원 음상 정위 효과를 제공할 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.02a
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• pp.139-142
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• 2008

헤드폰 또는 이어폰으로 오디오 청취 시 흔히 음상이 머리 내부에 맺히는 현상이 발생하게 되며, 이러한 현상을 음상 내재화(Inside Head Localization; IHL)라 한다. 오디오의 음상이 머리 주변 혹은 머리 내부에 맺히게 되면 공간감이나 입체감이 떨어지게 되어 음향의 현실감을 저하시키게 되며 또한 청취에 따른 피로도가 증가하게 된다. 이러한 음상 내재화 현상을 제거하여, 헤드폰/이어폰을 통해 오디오 청취 시 음상이 머리의 외부에 맺히도록(Out of Head Localization; OHL) 하는 기술을 음상 외재화(Sound Externalization) 기술이라 한다. 룸 임펄스 응답이 방향 큐와 연계하여 생성되었을 경우 외재화가 가능하다는 실험적 사실을 바탕으로 기존의 음상 외재화 방법은 일반적인 HRTF (Head Related Transfer Function)를 이용하여 외재화 필터를 구성해왔다. 본 논문에서는 구체마이크로폰을 이용하여 녹음한 멀티채널 룸 임펄스 응답을 기반으로 모델링 된 외재화 필터를 이용한 음원 외재화 방법을 제안한다. 또한 실험 및 결과 분석을 통하여 본 알고리즘의 전방 음원 외재화 성능의 우수성을 입증하고, 외재화 알고리즘 적용 후의원 신호 음상 보존 성능을 확인한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.71-76
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• 2000

On multimedia teleconferencing system existing a number of participants, face of the participants can beperceived by visual image. However, differentiation of each participant's voice and spaciousness sense are very hard since voice of all participants is processed with one dimensional data. In this paper, we implemented three dimensional audio rendering system using the HRTF(Head Related Transfer Function) and distance sense reproduction method and determined the optimal location of the participants for teleconferencing system. In the results of the listening test using elevation and azimuth angle, we showed that directional perception of the azimuth angles were better than that of the elevation angles. Specially, we showed that participant location using the HRTFS of the azimuth angle 10" , 90" , 270" and350" was efficient in teleconferencing system existing four participants. We also proposed that distance cue was used for enhancement of the reality and location of many participants more than five.ipants more than five.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.1
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• pp.21-29
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• 1999

This study was performed to identify the effect of the hydrosalpinx fluid on sperm motility. It has been reported that the patients with hydrosalpinx show the outstandingly lower success rate than other patients having infertility by different factors. It is unclear that the cause of it is influenced by hydrosalpinx fluid directly or by secondary chronic inflammation of endometrium. We wanted to know if the hydrosalpinx fluid influences sperm motility parameters directly such that it is related to the development of infertility. Therefore, using computer assisted semen analyzer (CASA), we observed, from February to July, 1997, how sperm motility, sperm progressive motility, sperm curvilinear velocity, sperm lateral head displacement, sperm straightness and sperm linearity change after treating normal sperm with hydrosalpinx fluid to evaluate sperm function on infertility. The result was that the study group (n=32) has the tendency to differ from the control group (n=32) on sperm motility, progressive motility, curvilinear velocity, lateral head displacement, straightness and linearity. We concluded that the hydrosalpinx fluid, with varying degree, directly has the harmful effects on sperm motility parameters, that is, curvilinear velocity, lateral head displacement and linearity of sperm which are related to the hyperactivation, hence decreased capacitation.

• The Journal of the Acoustical Society of Korea
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• v.30 no.4
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• pp.167-180
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• 2011

Recently, 3-D audio technologies are commonly implemented through headphones. A major problem of the headphone-based 3-D audio is in-the-head localization, which occurs due to the inaccurate Head-Related Transfer Function (HRTF). Since the individual measurements of HRTFs are impractical, there have been several researches for HRTF customization. In this paper, an efficient method of customizing HRTFs for the sound externalization is proposed. Firstly, it is determined which part will be customized in HRTF through psychoacoustical experiments. Then, the method controlling spectral notches and envelopes to provide individual localization cues are described. Since the proposed method is based on a critical-band rate, the structure is much simpler than that of previous studies, but still effective. The performance was evaluated through a series of subjective tests, and the results confirmed that the customized HRTF using proposed method could replace the measured individual HRTF successfully.