• Journal of the Institute of Convergence Signal Processing
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• v.2 no.3
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• pp.24-31
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• 2001

The K-L expansion is a method for compressing dimensions of features and thus reduces computational cost in recognition process. Also This is well known that features can be extracted without much loss of information in the statistical pattern recognition. In this paper, the method that effectively applies K-L(Karhunen-Loeve) expansion to feature parameters of speech is proposed to improve the recognition accuracy of the Korean speech recognition system. The recognition performance of a novel feature parameters obtained by the proposed method(K-L coefficients) is compared with those of conventional Mel-cepstrum and regressive coefficients through speaker independent connected digits recognition experiments. Experimental results showed that average recognition rates using the K-L coefficients with regression coefficients obtained higher accuracy than conventional Mel-cepstrum with their regression coefficients.

• MALSORI
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• no.44
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• pp.73-82
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• 2002

Channel distortion degrades the performance of speech recognizer in telephone environment. It mainly results from the bandwidth limitation and variation of transmission channel. Variation of channel characteristics is usually represented as baseline shift in the cepstrum domain. Thus undesirable effect of the channel variation can be removed by subtracting the mean from the cepstrum. In this paper, to improve the recognition performance of Korea connected digit telephone speech, channel compensation methods such as CMN (Cepstral Mean Normalization), RTCN (Real Time Cepatral Normalization), MCMN (Modified CMN) and MRTCN (Modified RTCN) are applied to the static MFCC. Both MCMN and MRTCN are obtained from the CMN and RTCN, respectively, using variance normalization in the cepstrum domain. Using HTK v3.1 system, recognition experiments are performed for Korean connected digit telephone speech database released by SITEC (Speech Information Technology & Industry Promotion Center). Experiments have shown that MRTCN gives the best result with recognition rate of 90.11% for connected digit. This corresponds to the performance improvement over MFCC alone by 1.72%, i.e, error reduction rate of 14.82%.

• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.13-20
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• 2001

In this paper, we propose a new digital audio watermarking scheme In the cepstrum domain. We insert a digital watermark signal Into the cepstral components of the audio signal using a technique analogous to spread spectrum Communications, hiding a narrow band signal in a wade band channel. In our proposed method, we use pseudo-random sequences to watermark the audio signal. The watermark Is then weighted in the cepstrum domain according to the distribution of cepstral coefficients and the frequency masking characteristics of the human auditory system. The proposed watermark embedding scheme minimizes audibility of the watermark signal. and the embedded watermark is robust to mu1tip1e watermarks, MPEG audio ceding and additive noose.

• The Journal of the Acoustical Society of Korea
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• v.7 no.4
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• pp.77-85
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• 1988

Many kinds of conditioning monitoring technique have been studied, so this study has inverstigated the possibility of checking the trend in the fault diagnosis of ball bearing, one of the elements of rotating machine, by applying the cepstral analyisis method using the adaptive noise cancelling (ANC) method. And computer simulation is conducted in order to verify the usefulness of ANC. The optimal adaptation gain in adaptive filter is estimated, the performance of ANC according to the change of the signal to noise ratio and convergence of least mean square algorithm is considered by simulation. It is verified that cepstral analysis using ANC method is more effective than the conventional cepstral analysis method in bearing fault diagnosis.

• The Journal of the Acoustical Society of Korea
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• v.16 no.2
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• pp.26-30
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• 1997

In this paper, the thickness measurement method of adhesive layers of multilayers using power cepstrum signal processing technique has been proposed. The peak values for reflected signal from each layer have been separated by power cepstrum technique. Therefore, thickness of adhesive layers have been measured by the intervals of peak signal. In the experiment, the adhesive layers of 0.5mm-0.75mm thickness using epoxy(2-Ton and Plastic Steel Putty(A)) between the aluminum and the brass were formed. The adhesive layer thickness which is calculated with data of reflected signal by ultrasonic pulse-echo method was within error 1.34% of the measured values.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1988.10a
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• pp.238-241
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• 1988

• MALSORI
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• no.50
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• pp.111-122
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• 2004

Automatic detection of laryngeal diseases by voice is attractive because of its non-intrusive nature. Cepstrum based approach to detect laryngeal cancer shows reliable performance even when the periodicity of voice signals is severely lost, but it has a drawback that it is not robust to channel mismatch due to different microphone characteristics. In this paper, to deal with mismatched training and test microphone conditions, we investigate channel compensation techniques such as Cepstral Mean Subtraction (CMS) and Pole Filtered CMS (PFCMS). According to our experiments, PFCMS yields better performance than CMS. By using PFCMS, we obtained 12% and 40% error reduction over baseline and CMS, respectively.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.55-58
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• 2000

본 논문에서는 화자 확인 시스템의 등록과 확인 과정의 채널 환경 불일치로 성능이 저하되는 문제를 해결하기 위한 새로운 정규화 방법에 대해 설명한다. 제안된 방법은 첫째, 입력 음성으로부터 효과적으로 채널을 추정$\cdot$보상하고 둘째, 스코어 정규화 과정에서 사칭자 모델로서 사용되는 world모델과의 차이를 채널 추정 및 화자 모델 생성에 효과적으로 사용하는 것을 목표로 한다. 이를 위해 입력 음성의 켑스트럼과 HMM world 모델의 파라메터인 평균 켑스트럼과의 차이를 통해 음소열에 종속적인 채널 켑스트럼인 Phone-Dependent Difference Cepstrum을 추정한다. 한편 입력 음성의 음소열은 world모델의 스코어를 얻는 과정에서 함께 얻어질 수 있다. 채널 추정 실험 결과를 통해서 가장 일반적인 채널 정규화방법인 CMS에 의해 추정된 채널에 비해 실제 채널과 유사하며 화자 고유의 특성을 왜곡시키지 않는 채널 추정이 가능함을 확인할 수 있었다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.153-156
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• 2000

본 논문에서는 음성 인식률 향상을 위한 여러 가지방법들 중에서 음성특징 파라미터 추출 방법에 관한 한가지 방법을 제시하였다. 본 논문에서는 청각 특성을 기반으로 한 MFCC(met frequency cepstrum coef-ficients)와 성능 향상을 위한 방법으로 GFCC (gamma-tone filter frequency cepstrum coefficients)를 제시하고 음성 인식을 수행하여 성능을 분석하였다. MFCC에서 일반적으로 사용하는 임계 대역 필터로 삼각 필터(triangular filter) 대신 청각 구조의 기저막(basilar membrane)특성을 묘사한 gammatone 대역 통과 필터를 이용하여 특징 파라미터를 추출하였다. DTW 알고리즘으로 인식률을 분석한 결과 삼각 대역 필터를 이용한 것보다 gammatone 대역 통과 필터를 이용한 추출법이 약 2∼3%의 성능 향상을 보였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.109-111
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• 2007

Community Noise has been great concerned in public. A road traffic noise has affected too much damage on quiet living environment. In this paper, the noise barrier effect on the street has been examned. As a tool of the path analyses, a cepstrum analyses of signal processing technique has been implemented.