Abstract: An electronic musical instrument includes an excitation signal generating device, a plurality of loop circuits and a coupling circuit. The excitation signal generating device generates an excitation signal in accordance with musical tone designating information. Each of the plurality of loop circuits at least delays an input signal in response to the musical tone designating information and repeatedly circulates the input signal therein. The excitation signal generated by the excitation signal generating device is supplied to at least one of the plurality of loop circuits as an input signal. The coupling circuits couples the plurality of loop circuits in accordance with a predetermined coupling form. At least one signal circulated in at least one of the plurality of loop circuits is output as a musical tone signal to be generated. The electronic musical instrument further includes a memory circuit which stores a plurality of coupling forms.

Abstract: A filter operation unit includes an operation circuit for receiving a digital tone signal and an operation parameter and digitally operating the tone signal with the operation parameter, a memory circuit for storing result of the operation and a connection switching circuit for establishing a filter operation algorithm by switching the mode of connection of the operation circuit and the memory circuit in response to a control signal. A control signal corresponding to a desired filter operation algorithm and an operation parameter for realizing a desired filter characteristic in the filter operation algorithm are generated by a control circuit and supplied to the filter operation unit. By switching the function of the filter operation unit, a filter characteristic corresponding to a desired filter operation algorithm can be selectively realized by employing one filter operation unit.

Abstract: A desired sound signal that is input from outside is amplitude-modulated or frequency-modulated with a signal of a predetermined characteristic which is generated from a signal generating source. A frequency characteristic controlling circuit controls the frequency characteristic of the modulated sound signal in accordance with a characteristic of a tone to be generated, and it outputs the controlled signal as a tone signal.

Abstract: An electronic musical instrument is disclosed wherein the musical tone parameter such as the tone volume, tone color, acoustic reverberation, pan-pot and the like can be varied over time. The invention provides an electronic musical instrument including an operational device, a memory, a readout section, a control section and a tone generator. The operational device can be implemented in a stick type operator for example. The operational device generates operational data which vary over time in response to operations applied thereto. The operational data generated by operational device are consecutively stored in the memory. The readout section can be implemented in a CPU for example and consecutively reads out the operational data from the memory. The control section can be implemented in a CPU for example and generates a musical tone parameter which varies over time on the basis of data consecutively read out from the memory.

Abstract: The musical tone synthesizing apparatus synthesizes a musical tone signal in response to the wind instrument and the like to thereby simulate a resonance tube providing with several sound holes each opened or closed by each finger of a performer. Herein, the input signal is delayed by the predetermined delay time, and then the predetermined operational process corresponding to the signal-scattering operation is carried out on the delayed signal. The coefficient used in this operational process is varied in response to the open/close state of each sound hole. Thus, the operation result can simulate the musical tone to be sounded from the resonance tube of the wind instrument and the like.

Abstract: A musical tone synthesizing apparatus provides a time-varying signal processing circuit the transfer function of which gradually varies over time in order to gradually vary over time the tone color of a synthesized musical tone. A number of time-varying signal processing circuits are presented. An interpolation-type-time-varying signal processing circuit is provided with interpolators for interpolating control parameters generated based on a desired musical tone, a signal processing circuit carrying out a signal operation based on the interpolated control parameters on an input signal incomming thereto.

Abstract: A musical tone synthesizing apparatus conducts musical tone synthesis based on the tone generation mechanism of an acoustic musical instrument, and generates quickly and accurately desired musical tones in response to the operation of the beginning of tone generation. The musical tone synthesizing apparatus includes a performance data generation mechanism which generates performance data in accordance with performance operations, an excitation circuit, which generates an excitation signal in correspondence with the performance data, and a signal loop circuit which delays the excitation signal by a fixed period and repeatedly cycles the excitation signal. The performance data generation mechanism, furthermore, supplies an initial excitation control signal, which is for the purpose of exciting the signal loop circuit, to the excitation circuit during the initial generation of a musical tone.

Abstract: An electronic sound processor creates reverberation effects using a simulated impulse function. The simulated impulse response is generated by combining frequency bands of white noise. The power of each band decays exponentially in time. The time constants are generated from the characteristics of a real or imaginary listening space. A reverberated sound signal is generated from an original sound signal by convolution of the original signal and the simulated impulse response. The method can adapted to generated stereophonic signals and to generate a forward and inverse reverb effect using only one set of multiplications.

Abstract: An electronic musical instrument has an electronic sound source of a physical model simulating the sound mechanism of an acoustic mechanical instrument, in particular, a stringed instrument of the bowing type. The electronic sound source is controlled according to tone pitch information and tone information determining a characteristic of a musical tone to be generated. A keyboard is provided as a data input device by which tone pitch is designated and on which a performance manner is expressed via initial touch and after touch. A memory stores two sets of performance information, each set containing bowing force and bowing velocity information. An interpolating unit operates to access the memory for carrying out interpolation between the two sets of performance information according to the performance manner, and produces respective interpolated performance information regarding bowing force and bowing velocity information effective to control the artificial sound source.

Abstract: A loop circuit including a delay element and an all-pass filter circulates a tone signal. A driving waveform is applied to the loop circuit. The delay element provides a delay time corresponding to the pitch of the circulating tone signal and the all-pass filter is capable of changing the phase of the tone signal corresponding to its frequency. Thus, the resulting musical tone can be controlled in accordance with touch, thereby enabling the simulation of vibration of pitch and the generation of non-harmonic components caused by touch in a natural musical instrument.

Abstract: The present invention provides a signal delay circuit for substantially steplessly changing a delay interval. The signal delay circuit is composed essentially of a delay controller, a first delay circuit, and a second delay circuit. The delay controller generates and outputs control data consisting of a real number bearing control information for controlling the delay interval, the real number consists of an integral portion and a fractional portion. The first delay circuit receives an incidental signal, delays the incidental signal for creating a first intermediate signal, and outputs the first intermediate signal, the first intermediate signal being delayed with respect to the incidental signal by an interval which is a product of a predetermined cardinal interval and the integral portion of the real number.

Abstract: A musical tone synthesizing apparatus for synthesizing musical tones generated by acoustic instruments. In the musical tone synthesizing apparatus, a closed loop circuit is provided to simulate the vibration of a vibrating element, for example, a string of piano. Additionally provided is a excitation and damping control unit for generating signals to be introduced to the closed loop circuit. When generating musical tones, the excitation and damping control unit generates an excitation signal corresponding to the excitation operation applied to the vibrating element from a excitation element, for example, a hamper of piano. When damping the musical tones, the excitation and damping control unit generates a signal corresponding to the excitation operation applied to the vibrating element from a damping element, for example, a damper of piano.

Abstract: Data compression apparatus and corresponding method used for decaying musical instrument sounds in a digital sampling instrument. The data compression technique according to the present invention provides for data compression of decaying musical instrument sounds that is designed to be stored in a small space, provide for adequate musical reproduction of the sound, and be reproduced using current data sample playback technology.

Abstract: A musical tone waveform signal forming apparatus comprises a waveform signal transmission section, a musical tone control signal input section and a pitch control section. The waveform signal transmission section comprises a plurality of signal transmission units which are connected in cascade one by one and each of which comprises first and second signal lines respectively serving as forward and backward paths of a waveform signal and a node portion for feeding back an output from the first signal line to an input side of the second signal line. At least one of the first and second signal lines serves as a signal delay line.

Abstract: Tone generation in conformity with the tone generating mechanism of actual rubbed string instruments is made to obtain musical tones rich in reality as generated by natural musical instruments. Performance information outputted from a performance manipulator is converted into tone generation parameter by parameter generating means. Excitation means generate an excitation signal corresponding to the string-rubbing style on the basis of the tone generation parameter. A loop circuit gives both acoustic and propagation delay of the string to the excitation signal to thereby generate musical tone signals.

Abstract: An electronic musical instrument for realizing touch at the time of the manipulating of a manipulator such as a keyboard faithfully reflected on the resulting musical tone. The electronic musical instrument has acceleration pickups respectively attached to keys in the keyboard, and tone synthesizing portions respectively driven on the basis of signals obtained by integrating acceleration detection signals outputted from the acceleration pickups.

Abstract: A single signal processor performs a pitch process which produces musical sound waveform data having a frequency corresponding to received pitch data, a filtering process for filtering the generated musical sound waveform data, and an amplitude process which controls the amplitude of a musical sound generated on the basis of the filtered musical sound waveform data in order to produce a musical sound. It simultaneously performs outputting the produced musical sound waveform data to a plurality of output terminals and an effect process which imparts an effect to the musical sound data. The signal processor outputs at least one of musical sound waveform data to which the effect is imparted and musical sound waveform data to which no effects are imparted, using at least one of an external and an internal effect circuit to thereby impart a variety of effects to the resulting musical sound.

Abstract: An electronic musical instrument suitable for synthesizing musical tones, comprises a musical tone control apparatus for generating velocity data and a musical tone generator for generating a musical tone signal having musical tone characteristics according to the velocity data. The musical tone control apparatus comprises an operation member which can be movably operated, a detector for detecting operation data according to an operation position or displacement amount of the operation member along its moving direction, a conversion memory for converting the operation data outputted from the detector into velocity data, and a control circuit for controlling musical tone characteristics on the basis of the velocity data outputted from the conversion memory.

Abstract: Timewise change of filter characteristics is realized by interpolating filter coefficients to be applied to a digital filter circuit with a function of time. Scaling parameters are generated in correspondence to the tone pitch of a tone signal applied to the digital filter circuit and a time function in the interpolation operation is variably controlled in accordance with the scaling parameters. The inclination of timewise change of filter coefficients obtained by the interpolation is thereby variably controlled and, as a result, the rate of change of the filter coefficients, i.e., the rate of timewise change of filter characteristics realized thereby, is variably controlled in accordance with tone color.

Abstract: A tone signal synthesizer for simulating musical tones of a brass instrument faithfully. A nonlinear portion and a pipe linear portion are combined to simulate a brass instrument. The nonlinear portion has a resonance circuit having a resonance frequency in the vicinity of the frequency of a musical tone on the basis of an upper model, and a resonance circuit having a low resonance frequency on the basis of an outer model. Not only oscillation in the frequency of the musical tone is made by the former, but the instability of a brass instrument upon starting of tone generation is simulated by the latter. Further, not only a random number generation circuit gives a random number component to a flow rate signal, but a function table and a multiplier make the level of the random number component proportional to the square root of the flow rate signal.

Abstract: An electronic musical instrument comprises a filter coefficient generator, including a control signal generator for receiving timbre information, tone range information and touch information and for generating the first and second parameters to control a filter characteristic; a trigonometric function generator for generating a trigonometric function value based on the first parameter generated by the control signal generator; and a filter coefficient computing circuit for computing the trigonometric function value generated by the trigonometric function generator and the second parameter generated by the control signal generator. The filter coefficient generator sequentially generates filter coefficients by computation and sends them to a digital filter to continuously change the filter characteristic of the digital filter, thereby producing musical tones.

Abstract: A musical tone synthesizing apparatus is designed to simulate sounds of the non-electronic musical instrument, particularly the wind instrument. Herein, a wave-guide network and an excitation-vibration portion are connected together in a closed-loop. The wave-guide network is configured by plural bi-directional transmission circuits each at least providing a delay element, while the excitation-vibration portion provides a feedback loop between its input/output terminals. The feedback rate of this feedback loop is adjusted by a control signal supplied from an external device. By merely varying this control signal, it is possible to change the resonance frequency and also vary the width of the hysteresis curve representing the input/output characteristics of the excitation-vibration portion. When simulating the sounds of the wind instrument, the control signal corresponds to the blowing pressure applied to the mouthpiece of the wind instrument.

Abstract: An electronic musical instrument includes an excitation circuit, a closed loop circuit, a characteristics analysis circuit and a control circuit. The excitation circuit generates an excitation signal in response to performance information. The closed loop circuit causes the excitation signal inputted from the excitation circuit to circulate thereabout musical tone signal. The closed loop circuit also has a delay circuit for delaying the musical tone signal for a predetermined time. The characteristics analysis circuit analyzes an input signal and generates a control signal corresponding to the result of the analysis of the input signal. The control circuit controls characteristics of the musical tone signal circulating in the closed loop circuit in response to the control signal. The musical tone signal circulating in the closed loop circuit is then outputted therefrom as a sound signal.

Abstract: A tone generator comprises a basic wave memory for storing a first basic wave data of a musical tone signal, a differential wave memory for storing differential wave data between the first basic wave data and a second basic wave data which is different form the first basic wave data, and mixing device for mixing the first basic wave data and the differential wave data. The musical tone signal is produced by using the mixing device which mixes the basic wave data and the differential wave data without using directly stored sampling data memory. Further a multiplier for multiplying said differential wave data by random factors is provided, the random factors being distributed with normalized probability, resulting in that wave data not only varying tone color at random, but also resembling as a whole the basic wave tone color can be obtained.

Abstract: There are provided a waveform generating section for generating waveform sample data at a frequency corresponding a designated pitch, a coefficient generating section for generating n coefficients that correspond to a desired interpolation characteristic, a characteristic-controlling section for changing the coefficients to be generated in the coefficient generating section so as to variably control the interpolation characteristic, and an interpolation operation section for operating the coefficients with n digital waveform sample data generated sequentially from the waveform generating section and synthesizing operated data to produce one sample data. With this arrangement, it becomes possible to control the interpolation characteristic and therefore a resultant filter characteristic in accordance with a desired mode, when generating a tone signal of a smooth waveform by waveform interpolation operation utilizing digital filter operation.

Abstract: A musical tone generating apparatus comprises an excitation signal generator, a signal processing device and loop gain controller. The signal processing device is electrically connected in a closed feedback loop with the excitation signal generator, via a delay unit. The loop gain controller controls gain of said closed feedback loop according to a lapse of time.

Abstract: An address signal generation circuit generates an address signal which changes at a rate corresponding to tone pitch of a tone to be generated. This address signal consists of an integer section and a decimal section. A tone waveshape data generation circuit generates tone waveshape sampled data in response to the integer section of the address signal. A filter coefficient supply circuit can generate data corresponding to filter coefficients of m orders and selects and supplies n filter coefficients (where n<m) in response to the decimal section of the address signal. In a relation n=m/d, for example, the filter coefficient supply circuit selects filter coefficients corresponding to n orders which are distant sequentially with an interval of d in response to the value of the decimal section of current address signal.

Abstract: An electronic music system which imitates acoustic instruments addresses the problem wherein the audio spectrum of a a recorded note is entirely shifted in pitch by transposition. The consequence of this is that unnatural formant shifts occur, resulting in the phenomenon known in the industry as "munchkinization." The present invention eliminates munchkinization, thus allowing a substantially wider transposition range for a single recording. Also, the present invention allows even shorter recordings to be used for still further memory improvements. An analysis stage separates and stores the formant and excitation components of sounds from an instrument. On playback, either the formant component or the excitation component may be manipulated.

Abstract: An electronic musical instrument capable of achieving a variety of performance mode. A manipulation region to be played with a hand manipulator is divided into regions of different performance modes. Tone signal parameters are generated differently depending on the selection of the performance region. Tone generator generates musical tone signals based on the tone signal parameters. The tone signal parameters are determined based on coordinate information on the manipulation region designated by the hand manipulator and pressure information applied on the coordinate position by the hand manipulator. The tone signal parameters comprise velocity information, pressure information and tone pitch information.

Abstract: A series of delay circuits are provided which receive tone signal sample data of plural channels supplied on a time shared basis, hold plural tone signal sample data of each channel and hold these plural sample data while sequentially delaying them. The series of delay circuits are connected in an endless manner to form a circulating loop and plural data selection circuits are provided at predetermined delay stages. Each data selection circuit performs a selection control as to whether new tone signal sample data should be loaded in the delay circuit loop or data in the delay circuit should be circulated. Tone signal sample data which are provided sequentially from the delay circuit loop after delay are sequentially operated with filter coefficients of plural orders and results of the operation are accumulated to obtain a filter operation output.

Abstract: An object of the present invention is to provide an electronic musical instrument which can generate a plurality of tones in spite of the inexpensive and simple structure thereof and can correct the quantity of phase delay of a closed loop in a physical model tone generator without use of any special processor such as a high-speed CPU or a dedicated numerical operation processor, not only to thereby attain performance effects of echo, chorus and the like but to simulate a performance style of repeating the operation of one string or key in the condition in which a tone corresponding to the string or key remains, without production of noise even when parameters for constituent elements of the physical model tone generator are respectively changed widely. The electronic musical instrument includes a driving waveform for storing a plurality of driving waveform data corresponding to performance information in advance, and a closed loop constituted by a shift register and a low-pass filter.

Abstract: The musical tone synthesizing apparatus simulating the musical tones of a natural musical instrument such as a piano. The apparatus contains a closed-loop circuit for simulating the vibration mechanism of the strings and a excitation circuit for generating excitation signals to the closed-loop circuit, so that the excitation circuit simulates the hammer striking the string. The apparatus also contains a scaling coefficient generating circuit for generating and supplying scaling coefficients to the excitation circuit, where the scaling coefficients represent the influence rate corresponding to the influence to be applied to the hammer by the string. In the excitation circuit, the excitation signals are multiplied by the scaling coefficients so that a slight difference of tone color is applied to the excitation signals with respect to tone pitch (or each key).

Abstract: A musical tone generating apparatus generates musical tones based on a signal outputted from a sound source and an envelope generator. The signal outputted from the sound source is processed by a digital filter in accordance with filter information responsive to a key-on signal. Filter information generating circuit generates delay time information corresponding to the time period which the digital filter needs to process and output an inputted data. The envelope is imparted to the signal outputted from the sound source with a delay from a key-on timing which corresponds to the delay time information to realize precise envelope rise portions.

Abstract: A musical tone waveform signal forming apparatus comprises a delay loop circuit, a filter circuit a drive signal generation circuit and a modulation control circuit. The drive signal generation circuit inputs a drive signal to the delay loop circuit so that a musical tone is formed in the delay loop circuit. The filter circuit filters the musical tone. The modulation control circuit changes the delay length of the delay loop circuit and the characteristics of the filter circuit thereby adding a modulation effect on the musical tone to be generated.

Abstract: A musical tone generating device is capable of simulating various special playing techniques for a stringed instrument in which the harmonic spectrums of produced sound is enhanced, or otherwise altered. The device includes a delay circuit wherein an input signal thereto is delayed and output; a closed loop circuit comprising multiple feedback pathways to which the output of the delay circuit is supplied and processed therein, after which the processed signal is returned toward the delay circuit as an input signal; an excitation device in response to a predetermined control signal, generating an excitation signal and supplying it to the closed loop circuit, such that the excitation signal corresponds to an excitation vibration in the stringed instrument being simulated; and a control device wherein the predetermined control signal is generated and whereby the delay interval of the delay circuit and the processing carried out in the multiple feedback pathways are controlled.

Abstract: A tone signal processing apparatus for time-divisionally reading out tone signal waveforms in units of different channels from a waveform memory for storing a plurality of kinds of tone signal waveforms each consisting of tone data at a plurality of sampling points. An arithmetic circuit for multiplying each of two input data with a predetermined coefficient, and adding the products, and a memory circuit for storing an output from the arithmetic circuit are arranged. The arithmetic circuit is alternately operated in two arithmetic modes, i.e.

Abstract: A musical tone generation device comprises a musical tone signal generator and a musical tone control device. The musical tone signal generator consists of an excitation circuit and a delay circuit which simulate the musical tone generation mechanism of a musical instrument. This generator has a hysteresis characteristic, so that the generator generates a musical tone signal having the hysteresis characteristic, in accordance with a musical tone control signal. While, the musical tone control device converts the musical tone control signal into other musical tone control signal which nullifies the hysteresis characteristic of the musical tone signal generator. Therefore, the musical tone signal generator generates musical tone signals without the hysteresis characteristic.

Abstract: A voice input to a microphone is converted by an A/D converter to a digital signal which is then delivered to a DSP, which extracts the notes of the input voice for determining same. The processing by the DSP includes bandpass filtering with a frequency corresponding to each note as the central frequency. A plurality of notes is processed on a time divisional basis to determine their respective notes. A new musical sound electronically corresponding to one or more notes extracted as the result of the note detection is then generated on a real time basis.

Abstract: An apparatus for synthesizing musical tones is provided with an excitation device and time delay device so as to form a loop circuit, and also, a noise generation device for generating a blowing noise signal when blowing a wind instrument, and noise mixing device for mixing the blowing noise signal with excitation signal corresponding to musical information output from the wind instrument are incorporated in the loop circuit, thereby the excitation signal is circulated in the loop circuit and mixed with the blowing noise signal.

Abstract: A musical tone synthesizing apparatus simulating a wind instrument includes an excitation circuit simulating a reed operation of a mouth piece portion, a resonance circuit simulating a resonance tube and a musical tone control circuit. The excitation circuit produces an excitation signal based on an input signal and a reflected wave signal transmitted from the resonance circuit. The excitation signal is input to the resonance circuit. The resonance circuit includes a bi-directional transmission circuit and a junction unit which is inserted into the bi-directional transmission circuit. The junction unit caries out a scattering operation corresponding to a scattering operation of compression wave of air which is occurred in the vicinity of the tone hole of the resonance tube. The excitation signal propagates through the bi-directional transmission circuit in a forward direction as a progressive wave signal.

Abstract: A musical tone synthesizing device employing an operator, for generating musical tone signals by a modulation operation process. The device also employs a waveguide combined to the operator, for generating a reciprocating signal including a delay circuit for delaying the signal inputted into the waveguide feedback path, and for feeding back the output signal of the delay means to the signal, reciprocating within the waveguide.

Abstract: A musical tone generating apparatus is provided for an electronic musical instrument. The apparatus comprises a musical tone signal generating device and a parameter controller. The musical tone signal generating device generates a musical tone signal characterized by a tone parameter whose value is supplied from the parameter controller. The parameter controller comprises a target value generator and an interpolation device, which operate independently. The target value generator generates a target value of the tone parameter to the interpolation device, and the interpolation device interpolates between a present value of the tone parameter and the target value, so that the present value is renewed consecutively.

Abstract: An electronic musical instrument provides a musical tone signal forming apparatus in order to sound a desirable musical tone. This apparatus includes a closed-loop wherein a signal is repeatedly circulating while being delayed by a delay circuit. In addition, the signal circulating the closed-loop is subject to the non-linear conversion. Thus, the signal picked up from the closed-loop can be controlled in response to the desirable non-linear characteristic. Preferably, the signal circulating the closed-loop is a musical tone waveform signal. For example, the musical tone waveform signal is varied in response to the feature of string, string bowing pressure and the like. Further, hysteresis characteristic simulating the statical and dynamic frictions to be occurred between the string and bow of the string bowing instrument can be imported to the non-linear characteristic.

Abstract: A filter calculating section has a plurality of basic filters formed on a time-divisional basis. The timbre of a musical tone signal is controlled by a memory section, an accumulator, a selector, an I/O assign section and a control section using the basic filters formed by the filter calculating section. A digital filter coefficient stored in a digital filter coefficient memory is read out using integer data output from a cutoff controller as an address. An interpolation circuit interpolates this digital filter coefficient on the basis of fraction data output from the cutoff controller. Based on the interpolated digital filter coefficient, the timbre of a musical tone signal is controlled.

Abstract: A musical tone synthesizing apparatus has a closed-loop configuration including an adder, a filter and a delay circuit. The adder adds its feedback signal to a signal to be synthesized which is applied from an external device. The filter constructed as the all-pass filter has a frequency characteristic by which a phase delay between its input and output signals is varied in response to a frequency variation of its input signal. Such all-pass filter includes a delay element having a delay time which is set longer than a predetermined unit delay time corresponding to a sampling period to be employed. Herein, the output of adder is fed back to the adder via the all-pass filter and delay circuit as the feedback signal. Thus, a signal circulating the closed-loop is picked up as a synthesized musical tone signal.

Abstract: A musical tone synthesizing apparatus is disclosed wherein an excitation signal corresponding to performance data is generated and supplied to a loop circuit. In the loop circuit, this excitation signal is delayed for at least a fixed time period and a repeatedly circulating muscial tone signal is generated. At the beginning of the generation of this musical tone signal, a initial signal with a frequency which corresponds to the pitch of the generated musical tone is supplied. As a result of this, in the loop circuit, resonant operation is carried out quickly in accordance with the initial signal.

Abstract: A musical tone waveform signal generating apparatus is used to generate the waveform signal full of variety which simulates the sound waveform of wind instrument. This apparatus provides a loop including first and second signal lines through which the waveform signal is circulated. Both of first and second signal lines are connected to a conversion portion which receives the waveform signal from the second signal line and a musical tone control signal which is used to control a musical parameter of a musical tone to be generated. The conversion portion effects the predetermined non-linear conversion on the waveform signal in response to the musical tone control signal so that a converted waveform signal to be obtained from the conversion portion is to be outputted to the first signal line.

Abstract: At least two sets of filter coefficients corresponding to different filter characteristics are interpolated by using a control signal for controlling tone color as a parameter of interpolation. Filter coefficients obtained by the interpolation are supplied to a digital filter to determine its filter characteristics and an input tone signal is modified in accordance with the filter characteristics thus determined. Filter characteristics of diverse variation as compared with the number of prepared filter coefficients can thereby be realized. Further, timewise change of filter characteristics can be realized by changing a parameter of interpolation with lapse of time or changing two sets of filter coefficients to be interpolated with lapse of time. Designation of filter coefficients can be made by designating coordinate data of coordinates having at least two axes.