| 摘要 |
1403072 Speech analysers PLESSEY CO Ltd 3 Oct 1972 45502/72 Heading H4R In a formant tracking system including two parallel paths each including an inverse filter and a formant tracker, the output of the formant tracker in each path being fed back to control the inverse filter in the other path, the absence of voiced speech is detected and used to set the formant trackers to specific rest conditions, as through they still has a speech input. As described the formant tracking system is of the type described in Specification 1,303,808 and the absence of voiced speech is detected in 2 by determining the level and frequency of the incoming speech signals and giving an output when the level is below a predetermined value and the frequency of the speech components above a predetermind frequency. The output of the voiced speech detector operated a switch 4 which disconnects the real speech signal input and replaces it with synthetic speech from synthesiser 6 having fixed formants F 1 , F 2 and F 3 . Alternatively the switch can connect voltage sources to the formant trackers to make them assume a particular output condition. If the trackers are of the ratio measuring type of Specification 1,337,254 a voltage source can be connected via respective resistors to the integrator amplifiers of the formant tracker. |
