| 摘要 |
A filter device has a variable frequency cut-off characteristic as well as a variable gain characteristic. To obtain these characteristics, a filtering operation is performed on data input thereto on the basis of a transmission function, which is defined by gain G for predetermined frequencies and a frequency fo corresponding to a phase at an intersection of a unit circle and a straight line intersecting at right angles a real axis passing a midpoint between a polar and a zero point on the real axis on Z-plane. An electronic musical instrument employing the filter device can change amplitudes of frequency components involved in musical tones on the basis of performance data, generating musical tones involving complex harmonics and having various tone colors, as a conventional acoustic instrument does.
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