• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1845-1851
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• 2007

Background noise and room reverberation are two causes of degradation in speech in listening situations. Many algorithms developed to enhance reverberant speech. In this paper we propose a dereverberation method for enhancement of speech using modified the linear prediction(LP) residual in reverberant room condition. The proposed dereberberation method based on the fact that the signification excitation of the vocal tract system takes place at the instant of glottal closure in voiced speech. Our method used delay information form each sensor, and we need reverberant signals from 3 sensors. We obtain a new LP residual signal using modified IP residual combination which derived form weighting of the LP residual and the Hilbert transform of LP residual. The nature of the coherently added Hilbert envelop has several large amplitude spikes because of the effects of noise and reverberation. This residual of the clean speech is used to excite the time-varying all-pole filter to obtain the enhanced speech. We achieved simulation of proposed algorithm for performance analysis in reverberation environment. The proposed algorithm improves substantially the quality of reverberant speech.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.489-498
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• 2018

In this paper, a target detection method based on beamspace-domain multichannel nonnegative matrix factorization is studied when an echo of continuous-wave ping is received from a low-Doppler target in reverberant environment. If the receiver of the continuous-wave active sonar moves, the frequency range of the reverberation is broadened due to the Doppler effect, so the low-Doppler target echo is interfered by the reverberation in this case. The developed algorithm analyzes the multichannel spectrogram of the received signal into frequency bases, time bases, and beamformer gains using the beamspace-domain multichannel nonnnegative matrix factorization, then the algorithm estimates the frequency, time, and bearing of target echo by choosing a proper basis. To analyze the performance of the developed algorithm, simulations were performed in various signal-to-reverberation conditions. The results show that the proposed algorithm can estimate the frequency, time, and bearing, but the performance was degraded in the low signal-to-reverberation condition. It is expected that modifying the selection algorithm of the target echo basis can enhance the performance according to the simulation results.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06c
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• pp.403-406
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• 1994

음성은 화자의 상태 및 주변 환경에 따라 그 특징이 다양하게 변화한다. 본 논문에서는 음성신호의 특징 파라미터로 널리 쓰이고 있는 mel-cepstrum에 대해, 단어내에서의 변화를 정규화함으로써 인식성능을 향상시키고자 하였다. mel-cepstrum이란 단어 전체에 대한 mel-cepstrum의 평균 값으로 normalize 시킨 것이다. 한국어 숫자음에 대한 인식 실험결과, 본 논문에서 제안한 정규화된 mel-cepstrum이 정규화되지 않은 mel-cepstrum에 비해 우수한 인식 성능을 나타내었다. 또한 잡음 환경하에서 비교 실험한 결과에서도 상대적으로 우수한 인식률을 보였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.197-200
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• 2009

본 연구에서는 한국과 중국의 부엌 공간 조명환경을 비교하기 위하여, 한국 115가구와 중국 70가구를 대상으로 실태조사를 실시하였다. 그 결과, 첫째, 부엌공간의 크기는 중국보다 한국이 좀 더 큰공간을 사용하고 있었으며, 싱크대와 식탁 높이는 차이가 크지 알았다. 둘째, 중국의 경우 국부조명을 사용하지 않는 비율이 매우 높게 나타났으며, 전반조명도 전반적으로 부족함을 알 수 있었다. 또한 부엌의 조도 측정결과, 싱크대의 KS 평균조도인 200[Ix]를 만족시키지 못하는 경우가 한국445[%], 중국63.1[%]로 나타났으며, 식탁의 경우 KS 평균조도인 400[Ix]를 만족시키는 경우는 한국과 중국 모두 10[%] 미만으로 매우 미약한 것으로 나타났다. 셋째, 부엌 공간 조명의 밝기정도와 만족도는 한국과 중국 모두 보통정도인 것으로 나타났으며, 실내환경의 문제점으로는 한국의 경우 열환경, 음환경, 조명의 순으로 나타났으며, 중국은 조명, 공기, 일조량의 순으로 나타났다. 또한 조명환경 측면의 문제점으로 양국 모두 밝기, 관리, 효율성 순으로 나타나 주택계획 시에 이러한 점에 주안점을 두어 조명환경계획을 할 필요가 있다.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.285-295
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• 2010

The frequency in which noise energy is generated, that is, the point where the preceding vowel ends is the cut-off frequency. Thereupon, this study intends to examine the correlations between, cut-off frequencies, cut-off frequencies changed by the following vowel, and cut-off frequencies and nasalance score, of fricatives and affricates with the subjects of children with the cleft palate and normal children. The subjects of this study are total 12 children residing in Seoul and Gyeonggi area. Six are the children diagnosed to have the cleft palate and whose chronological age are more than six, and another six are the normal children who are also more than six and whose chronological age and sex correspond to those of the former. Each subject was presented with nonsyllable environment and sentence environment(50 environment) of fricatives and affricates. Regarding meaningless syllable environment and sentence environment of fricatives and affricates, children with the cleft palate had lower cut-off frequencies than normal children. As a result of comparative study on correlations between cut-off frequencies and nasalance score of children with the cleft palate and normal children, it doesn't show statistically significant correlations in both meaningless syllable environment and sentence environment of normal children, but it has statistically significant correlations in sentence environment of children with the cleft palate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.358-359
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.360-361
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.602-603
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• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.606-607
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• 2013

• Korean Journal of Environment and Ecology
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• v.30 no.3
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• pp.344-352
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• 2016

The goal of this study was to identify the water temperature and sound environment of oviposition sites of the Huanren brown frog (Rana huanrensis), which breeds in valleys in early spring. The study was conducted in Chiak National Park, central Korea, between March 23 and April 24, 2015. Correlation analysis of the physical factors of oviposition sites revealed that the number of egg clutches was positively correlated (p < 0.05) with the water temperature and negatively correlated (p < 0.05) with the sound volume of the oviposition sites. However, no correlation was found between clutch number and the total area or depth of water. The water temperature of the oviposition sites was $2.2^{\circ}C$ higher on average than that of the mainstream (p < 0.001). To avoid the low early spring temperatures, R. huanrensis spawned in sites with accumulated water, in which the depths were less than 10cm and the temperature was relatively high. Further, eggs were spawned in clusters in small spaces to maximize the thermal insulation effect. In terms of noise levels, oviposition sites were found to be 6.9 dB quieter than the mainstream (p<0.001). In conclusion, R. huanrensis was found to spawn in warm, quiet, and small oviposition sites in valleys to avoid low early spring temperatures and loud water noise. This study is significant because it is the first to characterize the sound environment of amphibian oviposition sites.