Electronic musical instrument2009-10-12(32, 34) and a
data path chip module (36) to effect multiple partial (Fourier) synthesis, in conjunction with a sound modelling technique, to generate up to 240 independent partials and impress time-varying amplitude envelopes on them and select and apply them to sound generation, each partial being controlled by selected parameters of frequency, amplitude, phase and attack/decay rate. A modulo-sumdither and oversampling approach to noise reduction is utilized in connection with the
data path chip arrangement. Log sine addition is utilized to avoid multiplication apparatus ordinarily required to combine sine wave defining parameters.
Claims
What is claimed is:
1. Electronic musical instrument comprising in combination:
means defining a digitized waveform for utilization with multiple input parameter selections,
means for making parameter selections via a user interface to generate digital inputs,
means for generating logarithms of multiple parameters, adding the same and converting the sum to antilog equivalent and feeding back on itself to produce a sample sum and,
means for applying the sample to output device and further comprising:
means for modulating the sample sum by clipping the bit length of each digital word thereof by clip rounding off the most significant bits, from an original n bit length, and further reducing into p bit length usable as a data unit bytruncate-elimination of the most significant p bits of n.
Description
BACKGROUND OF THE INVENTION
The present invention relates to electronic means for music generation and more particularly has as its object the provision of such instrument with a sound engine comprising an architecture enabling the application of thousands of stored unitsof music digital data to rapid production of analog speaker-driving forms, utilizing practical solid state circuit means.
The invention is described below with reference to electronic piano usage, but is also usable in a number of other electronic musical instrument roles to provide, singly or combined, the sounds of a variety of instrument, elements of human voiceand other sound sources and in analogous instrument contexts not involving music or voice, but involving comparably varying waveform data.
Multiple Partial (Fourier) Synthesis is a technique well known in engineering practice. Any arbitrary periodic waveform (e.g., musical instruments' sound) may be reproduced by summing up a series of sine waves of appropriately determinedfrequencies, amplitudes, and relative phases. This technique allows great flexibility, much more so than subtractive synthesis (which starts out with a complex waveform and filters out unwanted spectral content) or wave-table synthesis (which can onlyreproduce whatever is in the table).
It is the object of the present invention to establish effective instrumentation using Fourier synthesis.
SUMMARY OF THE INVENTION
The musical apparatus of the invention inputs a stream of digital signals which represent a sequence of audio notes to be ultimately produced. The apparatus creates a sequential list of partials and impresses time-varying amplitude envelopes onthem, such that the sequential list completely characterizes the desired audio signal. A multiple partial synthesis, sometimes referred to as a Fourier Synthesis, is formed.
Each partial from the sequential list is digitally generated by stepping through a ROM containing ...
