| 摘要 |
<p>PURPOSE:To return the frequency characteristic of a microphone and to prevent reduction in the recognition rate by providing an oscillator outputting an acoustic signal of the voice frequency band, analyzing a signal outputted from the oscillator and correcting the analysis section or a path before or after the analysis section so that the result of analysis is a predetermined relation. CONSTITUTION:A filter bank 6 is the arrangement of some of band pass filters, and an attenuator 7 is given to the output so as to adjust the level of each filter output. At first, all the attenuators are set so that all the outputs are made to the same level. In the case of normal processing, the analysis result in a register 8 and the standard pattern of a dictionary 11 are compared by a comparator section 10. Since the frequency characteristic of the microphone is disturbed by the effect of reflection of the surrounding without any modification, a sinusoidal wave of the voice band (150-10kOMEGA) is swept from the oscillator 1 to drive the speaker 3 and sound is outputted from the speaker and it is received by a microphone 4 to correct the characteristic. When all the bands are finished for sweeping, the outputs of each filter stored in the register 8 are compared and the difference of adjacent registers is taken and the attenuator 8 is adjusted to decrease the difference.</p> |
