| 摘要 |
In a digital tone synthesizer of a type using digital data representing the amplitudes of a predetermined fixed number of sample points along one cycle of the audio waveform of a musical tone and an oscillator controlling the sampling frequency as well as the pitch of the tone, a digital filter for transferring the digital data to a digital-to-analog converter at the sampling rate. The digital filter, in response to applied input coefficient values, operates as a low pass or high pass filter in which the cut-off frequency is a predetermined harmonic of the pitch frequency of the tone. By changing the coefficient values, the cut-off harmonic can be changed for a tone independently of the pitch of the tone. Thus any tone of the musical scale may be filtered to modify the harmonic content independently of the pitch of the tone.
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