著者

久保 和良

出版者

独立行政法人 国立高等専門学校機構 小山工業高等専門学校

雑誌

小山工業高等専門学校研究紀要 (ISSN:02882825)

巻号頁・発行日

vol.41, pp.123-132, 2009-03-10 (Released:2020-10-09)

著者

久保 和良 青島 伸治

出版者

The Society of Instrument and Control Engineers

雑誌

計測自動制御学会論文集 (ISSN:04534654)

巻号頁・発行日

vol.31, no.6, pp.712-721, 1995-06-30 (Released:2009-03-27)

参考文献数

22

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Piano and guitar tone decay analysis has been carried out using reverberation responses calculated by Wigner distributions. The responses are investigated in comparison with record of the conventional short time spectra. The reverberation responses which are intimately related with the internal energy of instrumens represent 1) the envelope of tone decay without fluctuation induced by interference, reflect 2) mutual load effect associated with the oscillators, thus, clearly show 3) the gradients of energy decay curves, and are 4) less influenced by window function length. A guitar under investigation is shown to provide 1) two-step tone decay curve not caused by difference between decay rates of horizontal and vertical vibration modes of the strings (single string tone), and 2) multi-step energy curve with each step having much longer duration than the interference period (two string tone).On the other hand, the analysis of a grand piano reveals the following features:1) two power peaks in the spectra of aftersound are caused by different reasons from each other, 2) multistep energy decay curve is altered by performance style or piano condition, and 3) the partials are exhausted after absorbing energy of the other vibration modes.

著者

久保 和良

出版者

The Society of Instrument and Control Engineers

雑誌

計測自動制御学会論文集 (ISSN:04534654)

巻号頁・発行日

vol.42, no.8, pp.845-853, 2006-08-31 (Released:2009-03-27)

参考文献数

43

被引用文献数

2 2

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New method for estimating instantaneous parameters of sinusoid from its differential domain samples is proposed. Assuming the signal under estimation as a sine-wave, the concrete algorithm for estimating parameters by algebraic operations is shown in this paper. Numerical experiments show that the algorithm enables us to perform high speed estimation, and has the desirable results as follows: (a) Comparing with the Fourier analysis and the time-frequency distributions such as the Wigner distribution, since the proposed method is not under constraints of the uncertainty principle, instantaneity in time domain and high resolution in frequency domain can be achieved, (b) Comparing with the method of calculating the original instantaneous frequency from pre-envelope of the signal via Hilbert transform, the proposed method can offer the true instantaneous frequency depending only on the instantaneous information of the signal, (c) Comparing with the Prony's method, this method gives more instantaneous parameters with higher resolution without dropping into ill condition. The proposed method gives estimates without trade-offs of choice of method options, without constraint of the sampling theorem, and with tolerance against quantization error in the differential domain samples. On the other hand, this method has defects of fragileness against sampling delays in the differential domain, and intolerance to the signals that are not sinusoids. For the proposed method introduces the differential domain sampling, and is based on the identification of sinusoid under original definition of frequency, the ultimate instantaneity in estimating parameters of sinusoid is achieved.