| 摘要 |
<p>A sound pitch detection and display system identifies automatically a note being played without requiring assistance from a vocalist or musician. A sound signal transducer (11) detects an input sound wave and supplies it to a filter (13) having bandpass characteristics. The bandpass characteristics of the filter are provided by a high pass filter stage (72) followed by an automatic gain control amplifier (75) that in turn is followed by two stages of low pass filtering (76, 77). The low pass filter stages supply their output to an alternate positive peak voltage and negative peak voltage detector circuit (15, 78) that derives an output representative of the fundamental frequency of the input sound wave being analyzed. The output from the detector circuit is supplied to a microcomputer (16) which processes the signal for display (18) for use by a musician, vocalist or like person for analysis and instruction purposes. </p> |
