Koji Niimi

Electronic musical instrument utilizing recursive algorithm

Musical tone signals are produced in an electronic musical instrument by calculating the amplitudes at successive sample points of a complex waveshape and by delivering these calculated amplitudes one after another in time sequence. A recursive algorithm is implemented to calculate each amplitude, using one or more sets of parameters and also the calculated amplitudes for a plurality of the preceding sample points. This musical instrument can produce a variety of musical sounds which realistically simulate those of the various existing natural musical instruments including percussion instruments, simply by suitably determining the parameters.

Electronic musical instrument utilizing data processing system

A CPU of a computer, or preferably a so-called microprocessor controls the tone waveshape generation. A tone generator unit, an instrument keyboard unit, a tone quality control unit are connected to a common data bus to which the CPU and the associated memories are also connected. Thus, the tone generator unit may be considered as a terminal unit of a computer system. Hence, the freedom in selecting the algorithm for generating a waveshape and the freedom in selecting and changing the parameters related to the waveshape generation are substantially increased. And therefore a gradually changing waveshape is very easily generated in one embodiment of this invention.

Electronic musical instrument of wave memory reading type

An electronic musical instrument is provided with a plurality of wave shape memories storing different musical tone wave shapes of different memory sizes for different tone ranges. The memory for the treble tone is of a small size and that for the bass tone is of a large large size. When a key is operated in the keyboard, a memory corresponding to the tone range to which the operated key belongs is selected and read out. While successfully avoiding economically disadvantageous increase in the memory size of the wave shape memories, beautiful and clear musical tones can be obtained having different tone colors for different tonal pitches just like those generated by natural musical instruments.

Reverberation imparting device

A reverberation imparting device comprises a prememory storing an input signal, a level detection circuit responsive to data stored in the prememory for detecting presence or absence of the input signal, a data memory storing a delayed input signal delivered out of the prememory, a fixed type convolution operation circuit for producing a reverberation signal with respect to the data stored in the prememory by using an initial portion of parameters of a reflected sound, an adaptive type convolution operation circuit for producing a reverberation signal with respect to data stored in the data memory by using a plurality of parameters of more significant bits among the remaining portion of the parameters of the reflected sound, and an adder for adding outputs of the fixed type and adaptive type convolution circuits and delivering out the result of addition as a reverberation signal. In one aspect of the invention, the reverberation imparting device further comprises a frequency characteristics control circuit for controlling frequency characteristics of a reverberation sound and a frequency characteristics setting circuit for timewise changing filter characteristics of the frequency characteristics control circuit.

Electronic musical instrument by nonlinearly addressing waveform memory

In an electronic musical instrument wherein a frequency information related to the tone pitch of a depressed key is repeatedly accumulated and the progressing accumulated value is used to designate the addresses of a waveform memory device storing the waveform of a desired musical tone, the frequency information is varied with time instantaneously so as to vary the speed of addressing the waveform memory and thereby to vary the waveform read out from the waveform memory device, thus changing the color of the produced musical tone.

Electronic musical instrument with tone generation by recursive calculation

A digital type electronic musical instrument generates a tone signal consisting of a plurality of time-varying partial tone signals each by recursive calculation. A recursive calculator is of a simplified construction by arranging the amplitude term to be excluded from the recursive calculation and to be multiplied thereafter. A remarkable reduction in the memory units can be accomplished by arranging the pair of initial values for each partial tone function to be equal to each other by the introduction of a phase term into the periodic part of the partial tone function.

Reverberation characteristics measuring device

A device for measuring reverberation characteristics in a reverberation room by a digital squaring and integrating computation process. According to the invention, only a part of digital data of a large word length obtained by squaring and integrating a reverberation signal is selected out for computing the reverberation characteristics in accordance with a measuring environment such as integration time and duration of a test pulse. By this arrangement, circuitry for computing the reverberation characteristics can be made compact and time required for computing can be shortened without sacrificing the accuracy of measurement. Further, according to the invention, the level of an input signal can be computed and displayed by computing intermediate squared and integrated data at a certain time interval and adding this data with compensation data corresponding to a frequency band width of the input signal. The compensation data is automatically calculated in accordance with a set frequency of the test pulse so that a concise input signal level computation and display circuit can be provided.