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Cepstrum

About: Cepstrum is a research topic. Over the lifetime, 3346 publications have been published within this topic receiving 55742 citations.


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Proceedings ArticleDOI
John Makhoul1
01 Apr 1976
TL;DR: This paper presents a general analysis-synthesis scheme for the arbitrary spectral distortion of speech signals without the need for pitch extraction, and linear predictive warping, cepstral Warping, and autocorrelation warping are given as examples of the general scheme.
Abstract: The spectral distortion of speech signals, without affecting the pitch or the speed of the signal, has met with some difficulty due to the need for pitch extraction. This paper presents a general analysis-synthesis scheme for the arbitrary spectral distortion of speech signals without the need for pitch extraction. Linear predictive warping, cepstral warping, and autocorrelation warping, are given as examples of the general scheme. Applications include the unscrambling of helium speech, spectral compression for the hard of hearing, bit rate reduction in speech compression systems, and efficiency of spectral representation for speech recognition systems.

9 citations

Journal Article
TL;DR: In this article, a comparison is made between five analysis algorithms for calculating ultrasonic wave speed, including overlap, Hilbert transform, phase slope, cross correlation, and cepstrum algorithms.
Abstract: Ultrasonic wave speed measurements are required in many applications, including material property determination, microstructural characterization, and flaw detection of materials. The accuracy and repeatability of results are dependent on both the hardware used to propagate and receive the ultrasonic waveforms and on the analysis for calculating wave speed. In this study, a comparison is made between five analysis algorithms for calculating ultrasonic wave speed. The overlap, Hilbert transform, phase slope, cross correlation, and cepstrum algorithms are implemented using a commercial software package. Average wave speed and standard deviation are compared for ten materials. Each algorithm has calculated wave speed within 1 percent of the mean for all five algorithms. The most consistent results have been provided by the overlap, cross-correlation, and cepstrum algorithms, which have produced results within 0.2 percent of the mean for the three algorithms.

9 citations

01 Jan 2012
TL;DR: In this article, the regeneration of frequency response functions (FRFs) based on a previously-proposed cepstrum-based operational modal analysis (OMA) technique is discussed.
Abstract: This paper discusses the regeneration of frequency response functions (FRFs) based on a previously-proposed cepstrum-based operational modal analysis (OMA) technique. OMA differs from experimental modal analysis (EMA) in that it seeks to determine a structure's dynamic characteristics from response-only measurements, without precise knowledge of excitation forces. Response measurements, however, comprise both excitation and transmission path effects, which must be separated before the structural properties can be determined. The method employed in this paper achieves source-path separation with the cepstrum, which is able to deal with 'frequentially smooth' (not just frequentially white) inputs. After separation, the poles and zeros of the transfer function can be obtained by curve-fitting the transfer path cepstrum. But the FRF regenerated from these poles and zeros corresponds to a truncated model of the system, covering only a limited frequency range. The out-of-band poles and zeros affect the magnitude and phase of the in-band FRFs, and this distortion must be corrected in the FRF regeneration process. This paper focuses on that correction using data from a steel beam experiment. To do this, an 'equalisation curve' is used, based on a comparison of the regenerated FRF with a 'reference FRF', found with EMA or FEM techniques. The paper proposes a polynomial-fit approach to obtain the equalisation curves, resulting in excellent agreement between measured and OMA-regenerated FRFs. The techniques outlined in the paper have a number of potential applications, particularly in the fault diagnostics and structural health monitoring fields, where damage is often detectable by changes in the structure's FRFs.

9 citations

01 Jan 2006
TL;DR: In this article, the accuracy of the estimation of formant frequencies using Cepstral smoothing and LPC was evaluated using Matlab and the results showed that there is a wide range in the estimated frequencies for male and female speakers.
Abstract: This paper discusses the accurate measurement of formant frequencies using Cesptral and LPC method. Each algorithm was implemented with Matlab and was applied in the aim to evaluate the precision of both designed techniques. The conceived Cepstral algorithm is a frequency method based on picking peaks from the Cepstrally-smoothed frequency spectrum of the speech signal. Cepstral smoothing is a nonparametric method that attempts to remove the effect of glottal pulsing to obtain the spectral envelope corresponding to the vocal tract response. The obtained result, i.e. the Cepstrum, was then used to estimate the smoothed spectrum. Formant frequencies are estimated from the smoothed speech spectrum by adding constraints on the formant frequency ranges. The four highest peaks are typically classified as the first four formants. However, the LPC algorithm estimate formant frequencies from the all pole model of the vocal tract transfer function. The approach relies on the source - filter model supposing that the speech signal can be considered to be the output of a linear system. The frequency response of the filter has different spectral characteristics depending on the shape of the vocal tract. The spectral peaks in the spectrum are the resonances of the vocal tract and are commonly referred to as formants. The linear prediction analysis is the traditional method used to compute the model of the vocal tract. The obtained result, i.e. prediction coefficients, was then used to estimate formant frequencies. The obtained results show that there is a wide range in the estimated values of formant frequencies for male and female speakers. The presented work supply a comparison between the two techniques based on the coefficient of deviation, standard deviation and physiological results, in the aim to evaluate every method.

9 citations

Journal ArticleDOI
TL;DR: The new approach exceeds the performance of a formerly introduced classical signal processing-based cepstral excitation manipulation (CEM) method in terms of noise attenuation by about 1.5 dB and shows that this gain also holds true when comparing serial combinations of envelope and excitation enhancement.
Abstract: This contribution aims at speech model-based speech enhancement by exploiting the source-filter model of human speech production. The proposed method enhances the excitation signal in the cepstral domain by making use of a deep neural network (DNN). We investigate two types of target representations along with the significant effects of their normalization. The new approach exceeds the performance of a formerly introduced classical signal processing-based cepstral excitation manipulation (CEM) method in terms of noise attenuation by about 1.5 dB. We show that this gain also holds true when comparing serial combinations of envelope and excitation enhancement. In the important low-SNR conditions, no significant trade-off for speech component quality or speech intelligibility is induced, while allowing for substantially higher noise attenuation. In total, a traditional purely statistical state-of-the-art speech enhancement system is outperformed by more than 3 dB noise attenuation.

9 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202386
2022206
202160
202096
2019135
2018130