| 摘要 |
19 The disclosed method consists of: the cutting up, after sampling, of the speech signal into frames of a determined duration; the carrying out a first self-adaptive filtering of the sampled signal (Sn) obtained in each frame to limit the influence of the first formant; the carrying out a second filtering to keep only a minimum of harmonics of the fundamental frequency; and the comparing of the signal obtained with two adaptive thresholds SfMin(n) and SfMax(n), respectively positive and negative and changing as a function of time according to a predetermined relationship so as to choose only the signal portions that are: respectively above or below the two thresholds. It then consists of: the computation, on a predetermined number of fundamental frequencies or pitches M possible, of the self-correlation of the signal obtained at the end of the previous processing operation from a determined sampling instant No; the choosing, as candidate pitch M or fundamental frequency values, those that are equal in number to a predetermined number n corresponding to maxima of self-correlation; and the entering of the corresponding values of the self-correlation in a table of scores updated at each new self-correlation so as to choose, as a pitch value, only the value that corresponds to a maximum score.
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