Method and apparatus for generating musical tone signals

In an apparatus for generating a musical tone signal of the type comprising a plurality of channel means for obtaining a plurality of partial tone components corresponding to a musical tone to be produced and having different frequencies, and means for synthesizing said partial tone components to produce said musical tone, the improvement which comprises means for determining respective sampling frequencies that satisfy the sampling theorem regarding respective partial tone components;

• calculation reference signal generating means for producing a calculation reference signal having a frequency corresponding to the highest sampling frequency among said sampling frequencies;
• and
• means for determining ratios of said sampling frequencies of said partial tone components to the frequency of said calculation reference signal;
• at least one of said calculating channels calculating a partial tone component having the ratio of one at a period of said calculation reference signal, while remaining calculating channels combining a plurality of the partial tone components each having the ratio of less than one into a set wherein sum of said ratios does not exceed one, and calculating, on the time division basis, said set of the partial tone components at a period corresponding to said ratio.

An electronic musical instrument comprising:

• a keyboard having a plurality of keys;
• means for generating a plurality of partial tone components having frequencies corresponding to a depressed one among said keys, said partial tone components being allocated into at least two groups in accordance with the frequencies thereof and the amplitude contribution of each partial being calculated at different repetitive sampling cycles corresponding to the respective frequency grouping of said each partial;
• and
• means for producing a musical tone according to said partial tone components.

A keyboard musical instrument of the harmonic synthesis type in which constituent amplitudes of a plurality of partials are separately evaluated and summed to establish each sample point amplitude of the generated musical tone, and having regular calculation intervals at which each partial constituent amplitude may be evaluated, the improvement comprising:

• means for ascertaining into which of a small number of frequency ranges each of the constituent partials belongs,
• first means for evaluating the partials of the highest frequency range at each of said regular calculation intervals,
• second means for evaluating the partials of the next lower frequency range at every second calculation interval,
• third means for evaluating the partials of the next lower frequency range at every fourth calculation interval, and
• means for accumulating the evaluated constituent amplitudes of all partials to establish each sample point amplitude of the generated musical tone.