| 摘要 |
1,155,422. Speech recognition. NATIONAL RESEARCH DEVELOPMENT CORP. 18 Nov., 1966 [24 Aug., 1965], No.36233/65. Heading G4R. Apparatus for analysing complex waveforms, e.g. speech, counts the numbers of (a) zerocrossings and (b) positions of zero time-derivative of the waveform, in a predetermined time interval. Count (b) in conjunction with the difference of the counts (b)-(a) are particularly significant for speech recognition. The maximum positive amplitude of the speech waveform in the time interval and the distances between successive zero-crossings are also used. The time interval may be fixed or vary with the fundamental pitch period of the speech obtained by counting the number of positions of zero time-derivative between a peak in the waveform envelope and the first preceding zerocrossing. |
