| 摘要 |
A tone synthesizer generating a marimba effect in which two percussion notes are sounded alternately an ocatve interval apart, simultaneously with and in response to the playing of a sustained note by depressing a key. The marimba tones are synthesized by alternately, at controlled intervals, calculating master data lists of the amplitude values representative of points on the waveforms of the two marimba tones and converting the respective master lists to analog waveforms by feeding the data in series to a digital-to-analog converter. The master data list for each tone in calculated by multiplying a set of coefficients for each tone with a set of sinusoid values. The coefficients correspond in value to the relative amplitudes of the harmonics of the tone. By sounding one set of coefficients with the odd number harmonics all equal to zero, the two resulting tones sound an octave apart. By continuously scaling the harmonic values before multiplying with the sinusoid values of the waveform of the peak envelope, the two tones can be tailored to produce a percussive effect. |
