Continuously variable attack and decay delay for an electronic musical instrument

Abstract

Abstract A digital musical instrument incorporating the effects of attack and decay by appropriately scaling the digitally synthesized waveform information at the leading and trailing portions of the waveform envelope. Such an instrument would be capable of producing two attack and decay periods with only one attack and one decay period resulting in the normal audible effect. The system is particularly adapted for use in an electronic musical instrument in which a digital multiplexed signal is generated by actuation of the keys of the instrument. The attack and decay periods generated by actuation and deactuation of the keys are processed such that each period is divided into "n" scale factors spaced in time, each such scale factor being associated with a different level of the waveform envelope. The scale factors cover the range of waveform envelope from zero to full scale. Upon receipt of a clear pulse, the digital counter begins counting, and would terminate the count upon reaching "n". If prior to the full count of "n", an additional clear pulse is generated, the counter resets to zero count and begins to count up again. For example, the clear pulse generated by a key actuation causes the attack and decay counter to be reset, thus beginning the attack mode and setting a flip-flop whose operation causes the scale factor to produce a zero amplitude waveform resulting in no audible sound production. At some predetermined count, a counter output decoder then generates a second counter clear pulse resetting the counter and the gating flip-flop thereby allowing the "n" scale factors to propagate through and produce an audible attack. The result is a delay time from the time of key actuation until the propagation of audio system output. The same principle applies to the decay mode. Upon deactuation of the key, the first set of "n" scale factors are forced to maintain full scale factor value and the second decay period is processed unaltered through the system producing the audible decay.

Inventors

• 👤 John Thomas Whitefield

Bibliographic Details