| 摘要 |
1,208,262. Speech recognition. ELECTRIC & MUSICAL INDUSTRIES Ltd. 20 Dec., 1967 [24 Sept., 1966], No. 42728/66. Heading G4R. Voice-operated apparatus comprises soundrecognition means including means responsive to the sound to define intervals dependent on the period of the basic frequency of the voice, and means for counting the respective numbers of cycles of oscillation occurring in at least two frequency bands during the intervals. The speech signal at 1, after amplification. 2, 4 and attenuation 3 with slow and fast automatic gain control (A.G.C.) as shown, is fed to a low-pass filter 6 (below 700 c/s.) and a highpass filter 8 (over 700 c/s.) which feed A counters 7 and B counters 9 respectively. A counters 7 comprise two counters which count up and down respectively for an interval (viz. cycle of the basic speech frequency in the case of voiced phonemes and 10 m.secs. in the case of unvoiced phonemes, the latter being indicated if the up-counting P counter (see below), reaches 90), under control of selector 12 controlled by voicing detector 10. At the end of the interval, the counts are supplied to a decoder 26, the counter which was counting down is reset to zero and the roles of the two counters are reversed for the next interval. Thus in each interval, the counters measure the number A of oscillations from filter 6 and the change AA in this number since the last interval. B counters 9 perform the same functions for the output of filter 8. P counters 13, driven by an oscillator 14, are controlled like the A counters, and provide the basic speech pitch P and the change in this AP since the last interval. Equality of the two P counters, indicating the middle of the interval, is used to switch counters DA, DB from a count-up mode to a count-down mode. These counters, which are driven from the filters 6, 8 respectively, are reset to zero at the end of each interval and measure damping of the A and B signals. Counters T1, T2, T3 count the number of intervals in which AA = 0, AB = 0 and A = B = 0 (silence) respectively. Counters at 19, 20 measure the extent of glides i.e. changes in A and B respectively taking place between the steady states, the divide-bytwo circuits 24, 25 being responsive to the steady states of A and B as indicated to T1 and T2. G counters respond to the output of amplifier 4, rectified at 5 and converted to digital form at 17, to indicate the amplitude and change in amplitude of the speech signal. Decoder 26 responds to the counter outputs to identify successive phonemes and control a phonetic typewriter 27 (or feed a computer). |
