• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.810-818
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• 2014

In this paper, we propose a stereophonic sound system using multiple smartphones. In the conventional sound systems using smartphones, all devices play the same signal so that it is difficult to provide true stereophonic effect. In order to solve this problem, we propose a novel sound system which can generate a virtual sound source at any location in such a way that smartphones at different locations play different signals with amplitude panning. By using the proposed system, we can generate more realistic stereophonic effect than the conventional system, and can control the sound effect by user's command. We developed the proposed system using commercial smartphones and verified that the developed sound system effectively provides the desired stereophonic effect.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.160-163
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• 1992

• The Journal of the Acoustical Society of Korea
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• v.16 no.3
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• pp.57-63
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• 1997

This paper proposes a new stereophonic acoustic echo canceller to preven the performance degradation at the instant of far-end talker's movement or change in transmission room environment in stereophonic teleconferencing system. In stereophonic acoustic echo canceller, the filter coefficients of the adaptive filters for echo cancellation do not have unique solutions and not converge to their optimum values. Therefore, the change of the far-end transmission room environment leads to degradation of ERLE(Echo Return Loss Enhanceement). Moreover, their computational complexity increases as the number of the filter coefficient increases, and their adaptive filters converge very slowly. So the real-time implementation is very difficult. To overcome these problems we propose a pre-processor consisting of an adaptive filter for making pseudo stereophonic signal, and it results in improved performance at the instant of environment change at far-end side and reduction of the total complexity.

• The Journal of the Acoustical Society of Korea
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• v.18 no.6
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• pp.17-30
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• 1999

This paper proposes a new stereophonic acoustic echo canceller to prevent impairments on the voice quality and to remove acoustic echo effectively appearing in stereo environment at the instant of abrupt change of the transmission room environment in teleconferencing system. In stereophonic acoustic echo canceller, the major defective problems are the large computational complexity of estimating echo path systems due to the long impulse response of the true echo paths and the performance degradation of echo canceller due to large correlation between dual stereo signals. Moreover, the change of the suboptimal solution for the echo canceller was considered as a critical deficient factor on to the performance of stereophonic echo canceller. To overcome these problems, this paper proposes pseudo stereophonic acoustic echo canceller using Hyper-plane projection algorithm, which shows the robustness to the environment change of the transmission room and the efficiency of computational complexity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.27-28
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• 2010

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.139-145
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• 2013

In this paper, the problems of the conventional amplitude panning method for a stereophonic panning system are analyzed. We observed that the distortion showed a feedforward comb filter response. As a remedy to this distortion, we propose a stereophonic panning system using a feedback comb filter. The comb filter is designed to minimize the difference between interaural level difference(ILD) of the proposed system and that of HRTF because ILD is most salient cue for the perception of the source direction. The proposed system is configured to operate selectively for the frequency band related to the source direction. The performance of the proposed system is verified by subjective listening tests.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2004-2007
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• 2002

In the linear combination type stereophonic echo canceller, it is known not to converge the coefficient vector of the adaptive filter to a correct echo path. In this report, we analyze the convergence value of the filter coefficient vector of the stereo echo canceling algorithm using input signals of all channels in relation to this problem. In this analysis, one of the two inputs to the un-known system and adaptive one are assumed to be a delayed and attenuated version of the other signal as a model of the input signal with a strong cross-correlation. As a result, it is shown for the coefficient vectors not to converge to echo paths, and nor to converge to the value which depends on the time delay and the attenuation of the input signal. We show that the computer simulation result are corresponding to our analytical results.

• 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.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.181-182
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• 2007

Wireless home theater and speaker system was designed. That has 20W output per channel, 0.1% THD (Total Harmonic Distortion) and automatic algorithm avoiding noise. The 3D stereophonic sound was realized through the wireless 5.1channel speaker system designed. That could be secured 0.4% improvement effect of THD compared with wire speaker systems. Specially in transfer sound with wireless, Frequency Hopping Spread Spectrum was superior than Direct Sequence Spread Spectrum in household electric appliances and wireless internet environment that radiated noise similar with ISM Band using 2.4GHz.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.147-150
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• 2013

UHDTV 시스템의 개발로 오디오에서도 보다 몰입감 있는 멀티채널 오디오 시스템에 대한 관심이 높아지고 있다. 이에, 과거 ITU-R에서 표준이 제정되어 극장 및 HDTV 등에 폭넓게 활용되어 온 5.1채널 대비 elevation 채널을 포함한 더 많은 채널 수를 사용하여 청취자에게 궁극의 몰입감을 줄 수 있는 멀티채널 오디오 시스템이 여러 표준화 단체를 통해 논의되고 있다. 이에 본 논문에서는 ITU-R에서 이루어지는 Advanced Multichannel Stereophonic Sound System 표준화 논의를 중점적으로 살펴보기 위하여, ITU-R의 구성과 현재까지 논의된 이슈 및 앞으로의 전망 등에 대해서 논하고자 한다.