| 摘要 |
In an electronic musical instrument, such as an electronic organ, the speech characteristics of reed organ pipes are simulated by applying pulses produced by key-actuated tone generators, which pulses are preferably narrow as compared to their repetition frequency, to a low-pass filter, the pass characteristic of which has a relatively sharp knee and a very rapid rate of rolloff, thereby to sharply attenuate the harmonics contained in the pulse which have frequencies above the cutoff frequency. The resultant tone passed by the filter is surprisingly reed-like in character, and by changing the cutoff frequency, reed-like voices of differing properties, imitative for example, of an organ Oboe tone, an orchestral Oboe tone, a Clarinet, a Kinura or a Trompette are obtained. The change in pitch that occurs in a reed organ pipe when the reed is just opening or just closing, which contributes significantly to the unique sound of reed pipes, is simulated by automatically adjusting as a function of time the cutoff frequency of the filter from its lowest cutoff frequency when no keys of the organ are played to the higher cutoff frequency appropriate to produce the desired reed voice. A single automatic filter can be used for all of the notes over a range of many octaves, or separate filters can be used for smaller groups of notes including, for example, some or all of the notes in a single octave. Organ tones simulating "flue" pipes may be produced simultaneously from the same tone generators by conventional filter means.
|
