Abstract: A sound generation device used in a public space generates tone data corresponding to a change in environment such as environmental noise, temperature, brightness, and the like. The sound generation device includes a detector for detecting environmental noise, temperature, brightness, and the like, and forms tone control data on the basis of the detected environment information. Tone parameters to be supplied to a tone generation LSI or a sound effect DSP are controlled according to the tone control data, thereby selecting and controlling a play No. of tone sources, tone color, tone volume, tempo, reverberation, and the like of tones or music tones to be generated.

Abstract: A touchscreen interface for a sound processing system, such as music synthesizers, which has a display panel and a touch sensitive panel overlying the display panel, includes an icon which represents an adjustable parameter used by the processing system. The processing resources supply a variable adjustment display to the display panel in response to a touch on the position of the icon, using pop-up slider or pop-up knob motif. The variable adjustment display overlies the interface display and has a size on the touch sensitive panel larger than the size of the icon to facilitate manipulation of the variable using a finger over a significant range of values. The variable adjustment display pops up when touched to obscure a portion of the graphical display used for the interface. When the variable is adjusted using the touch sequence, the variable adjustment display is removed, and the interface display is left unobscured.

Abstract: An envelope extracting circuit extracts an envelope from the waveform sampled by a musical tone sampling circuit, and stores the envelope data into a memory. An envelope approximating circuit approximates the envelope data as stored in the memory by the function data such as linear or exponential function data. The original envelope is approximated by a limited number of function waveforms whose characteristics change at switching points.

Abstract: In a musical tone synthesizing apparatus, employed by an electronic musical instrument, an excitation signal circulates through a waveguide to form a musical tone signal corresponding to a synthesized musical tone. The waveguide is configured by a loop circuit containing an adder, a delay circuit, a filter and an amplifier. A delay time used for the delay circuit is determined in response to a tone pitch of a musical tone to be produced, while a filter coefficient used for the filter is determined in response to a tone color of the musical tone to be produced. A multiplication coefficient used for the multiplier is generated in accordance with one of the tone pitch and delay time; or the multiplication coefficient is computed on the basis of the tone pitch and a decay rate which is set by a performer. In addition, a different multiplication coefficient can be generated in response to a state of an envelope waveform of the musical tone to be produced.

Abstract: A musical instrument produces nineteen tones in each octave, and the nineteen tones have respective fundamental frequencies regulated to a geometrical series of .sup.19 .sqroot.2 so as to be highly harmonized without difficult in performance.

Abstract: According to the invention, a plurality of pieces of frequency modulation information are weighted independently and then synthesized. The individual pieces of synthesized frequency modulation information are weighted independently, and individual pieces of sound data that have been generation speed controlled according to the individual pieces of frequency modulation information are synthesized. In this way, the individual pieces of frequency modulation information are weighted independently. Thus, the individual weighting processes may be changed in various ways without mutual restriction to produce for various changes in the frequency modulation.

Abstract: A musical tone synthesizing apparatus synthesizes musical tones by simulating the tone generation construction of an acoustic musical instrument. The acoustic musical instrument comprises of a tone generating element and a tone generating operator for exciting the tone generating element, thereby creating reciprocally propagating vibration within the tone generating element. The musical tone synthesizing apparatus has a parameter producing portion which automatically produces a plurality of control parameters used for controlling a simulation of the acoustic musical instrument in response to operational information representing the operation applied to the acoustic musical instrument by a performer, musical tone synthesizing portion which synthesizes a musical tone of the acoustic musical instrument, wherein the operation of the musical tone synthesizing portion is controlled in accordance with the control parameters. The parameter producing portion includes, for example, keyboard apparatus having a keyboard.

Abstract: An electronic musical tone synthesizing apparatus includes a damper pedal and an envelope generator. The envelope generator imparts an envelope to a musical tone to be produced. When the termination of the musical tone is designated, the envelope generator imparts a decaying envelope thereto. If the damper pedal is depressed during the processing of the decaying envelope, the decaying rate becomes slower. This leads to the performance of sustaining effects such as in an acoustic piano.

Abstract: An envelope generator for an electronic musical instrument, in which a current value of the envelope approaching asymptotically to a target level, using a subtracter means for subtracting from data representing the target level in a floating point representation, data representing the difference between the target level and the current value in a floating point representation with deeming these data as fixed point data each having a decimal point between an exponent part and a fractional part, and a comparator for comparing the output of the subtracter means with a predetermined constant, and for judging that an envelope phase transfer condition is met if the output of the subtracter is greater than the constant. The envelope generator can achieve a phase transfer control function substantially similar to prior art envelope generators by a small amount of hardware.

Abstract: When playing a wind instrument such as a clarinet, noises are inevitably or intentionally generated under effect of a turbulent flow contained in an air-pressure wave propagated through a resonance tube of the wind instrument. In response to an accurate simulation of a noise behavior, particularly, a behavior of the turbulent flow contained in the air-pressure wave, a musical tone synthesizing apparatus artificially produces a noise signal by use of a white-noise signal having the predetermined uniform spectral distribution. Herein, frequency characteristic and amplitude characteristic of this noise signal are controlled to be varied in response to an excitation signal which is created responsive to performance information representing the breath pressure applied to a mouthpiece of the wind instrument. This excitation signal is delayed by the predetermined delay time while it is circulating through a loop circuit.

Abstract: A sound synthesis process. The invention relates to an additive sound synthesis process, as shown in FIGS. 1A and 1B, in which sample blocks (16) are determined by performing the inverse Fourier transform of successive frequency spectra. The time-superimposed sample blocks (16) are added in order to form a sequence of samples representing the reconstituted sound wave.

Abstract: A system for use in an electronic musical instrument, which system includes a musical sound generating unit for generating a musical sound, and a detection unit for detecting that the magnitude of the musical sound data generated by the musical sound generating unit exceeds a processing capability, on the basis that the value indicated by the most significant bit prior to data processing not equal to that after data processing. A maintaining unit is also included which forcibly maintain the level of a signal representing the musical sound data at a maximum amplitude thereof, on the basis of the result of the detection effected by detection unit.

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 preferential order of channel vacating is determined according to a musical character of musical tones having assigned channels, thus permitting a channel assignment which does not depart from the harmony of the musical tone. The greater the number of tones which are equivalent in musical character, the more readily channels can be vacated for new tones, and tones with fewer equivalent tones in musical character may remain assigned. The channel selection may also be limited for low envelope level tones.

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: 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: A musical-tone signal controlling apparatus includes a processor which executes a musical-tone controlling process on an input musical-tone signal supplied to the processor, the processor including a delay unit which executes a delay process on the input musical-tone signal; a first discriminator which determines whether or not the input musical-tone signal to be supplied to the processor has become null; a second discriminator which determines whether or not the output musical-tone signal processed by the processor has become null; and a reset circuit which automatically resets the delay unit when the second discriminator determines that the musical-tone signal processed by the processor has become null after the first discriminator determines that the input musical-tone signal to be supplied to the processor has become null.

Abstract: An electronic musical instrument is provided with a touch data generating device and a reverberation unit which generates a reverberation signal. The reverberation unit generates the signal correspond to the musical tone signal based on the touch data. The reverberation unit has a reverberation parameter forming device for forming a reverberation parameter which controls the reverberation signal based on the touch data. The parameter includes a delay period for a delay element and/or a coefficient for a multiplier. The musical instrument is allowed to add a mixing device to it, for mixing the musical tone signal and the reverberation signal. The musical instrument is also allowed to have a channel detecting device for detecting the number of instructed channels in place of the touch data generating device, thereby the reverberation signal being controlled by the number of the instructed channels.

Abstract: A musical sound waveform generator includes a carrier signal generating unit, a modulation signal generating unit, a mixing controlling unit and a waveform outputting unit. The characteristics of the carrier signal from the carrier signal generating unit are determined such that the musical sound waveform generated by the waveform outputting unit is a sine wave or a cosine wave with a single frequency, where the mixing ratio of the modulation signal is made O by the mixing controlling unit. Therefore, the mixing controlling unit presets the mixing ratio of the modulation signal to be O, making it possible to generate a musical sound waveform which is only a sine wave or a cosine wave of a single frequency. During the performance, the mixing ratio can, for example, be determined at a high value immediately after the start of sound generation and thereafter reduced to near O with time.

Abstract: The present invention relates to an envelope signal generator for electronic musical instruments, and more particularly to an envelope signal generator that generates natural envelopes from which digital noises are removed substantially by obtaining a difference between a current value and a targeted value and then generating a corresponding value for compensating the difference.

Abstract: A parameter signal generator including a parameter generating information storing unit for storing parameter generating information necessary for generating a parameter signal, and a parameter signal generating unit for generating a parameter signal. The parameter generating information is serially read from the parameter generating information storing unit and the thus-read parameter generating information is preset in a parameter signal generating unit other than the parameter generating information storing unit. Therefore, the parameter signal generator includes a storing unit other than the parameter signal generating unit, and accordingly, a general-use memory can be employed as the storing unit, to substantially lower cost. The processing of generating and radiating musical sounds can be performed at a practically required speed by employing a high speed processor as a central processing unit.

Abstract: An envelope waveform generation apparatus comprises an envelope waveform signal generator for forming an envelope waveform signal, a specific position setting member for setting a specific position, a position comparator and a key OFF controller. When a key OFF event is detected, the position comparator compares a position and/or level on the envelope waveform with those of the specific position, and the key OFF controller decays the level of the envelope waveform signal in the shape of a predetermined key OFF waveform, or delays key OFF processing by the envelope waveform signal generator on the basis of the comparison result.

Abstract: A device(timer) is provided for measurement of lapse time from a predetermined portion of a first tone assigned to a tone production channel. When a new(second) tone generation request is given to the tone production channel the tone being generated is force-dumped. The time required for force-dump, namely the waiting time until the new musical tone is generated is decided based on the count value of the timer. Upon the lapse of this waiting time the new musical tone is generated at the above-mentioned channel. Thereby the waiting time is best controlled.

Abstract: A waveform data storing unit stores waveform data only at steps midway among a top zero level step and originally sampled steps at every sampling period from the top zero level step. An output means is included for outputting the waveform data at a moment staggered from another moment, at which the waveform data at the top zero level step and the originally sampled steps are ordinarily read out, by a period of time corresponding to half a step. The occurrence of a difference in phase of the read-out waveform is prevented without the need of a data correction unit. The waveform data storing unit stores midway-step data which are averages of waveform data at adjoining originally sampled steps and difference data representing the difference between the waveform data at the originally sampled steps and the midway-step data. A fine waveform can therefore be obtained while using a smaller quantity of data.

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: 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: An envelope generating apparatus comprises a work memory, a buffer memory, an envelope generator, a writing circuit, and an end signal generator. The work memory stores parameters including a target level LV and an envelope speed parameter SP for generating an envelope signal of a predetermined phase. The buffer memory stores parameters including a target level LV and an envelope speed parameter SP for generating an envelope signal of a phase following the predetermined phase. The envelope generator generates an envelope signal based on the parameters stored in the work memory. When the envelope generator completes the generation of the envelope signal of a predetermined phase based on the parameters stored in the work memory, the writing circuit writes the content of the buffer memory into the work memory.

Abstract: Changes in vibratory position of a batter head of a percussion are detected to output a decay vibration waveform by a detector. A tone source controller sequentially generates a plurality of tone source control codes on the basis of the decay vibration waveform data along time lapse. A tone source circuit controls a reading operation of digital waveform data of percussion tones stored in a waveform memory, and modification of readout data on the basis of the tone source control codes, to generate a tone waveform signal.

Abstract: An electronic keyboard instrument having a performance pad, a detector, a memory, and a sound system. The detector detects a key touch of a key depressed to assign a percussion tone to the pad. The memory stores the key touch detected by the detector with the percussion tone of the depressed key. The sound system produces the stored percussion tone in accordance with the key touch stored in the memory.

Abstract: A tone generating apparatus comprising a first tone signal generator including the same number of oscillators as a polyphonic number each for generating a tone signal of that tone component of tone components constituting a musical tone which has a relatively long tone-ON time; a first assigner for assigning tone generation to one of the oscillators of the first tone signal generator; a second tone signal generator including oscillators each for generating a tone signal of a different one of the tone components constituting a musical tone than the tone component having a relatively long tone-ON time, a quantity of the oscillators being less than the polyphonic number; and a second assigner for assigning tone generation to one of the oscillators of the second tone signal generator, whereby when a tone generation is specified, a tone signal output from one of the oscillators of the first tone signal generator assigned by the first assigner and a tone signal output from one of the oscillators of the second tone

Abstract: A musical tone generating apparatus generates a musical tone based on performance information generated by performing a keyboard and the like. The performance information functions to designate a first start timing of generating a musical tone signal and a second start timing of releasing a musical tone signal. Then, a period between first and second start timings is measured based on the performance information. Thus, one or more musical parameters of the musical tone is controlled in response to the measured period. Preferably, the musical parameter is the pitch, tone color, tone volume or musical effects such as portamento.

Abstract: An acoustic signal synthesizer stores a plurality of different acoustic data and includes a separate D-A converter connected to receive each of the different acoustic data. The D-A converters are responsive to separate envelope generators for controlling their respective outputs. A controller controls the output of the acoustic data to the respective D-A converter and simultaneously controls the respective envelope generator output. The output of the converters are mixed.

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 method for processing a waveform includes the steps of dividing an original musical tone into head data, mix data, and loop data. The data is subjected to several processing steps, including cross-fade mixing. All processing steps are carried out before the processed waveform is stored in memory. Therefore, when the stored data is read out to reproduce the original musical tone, no interpolation steps are required to link the head, mix, and loop data together because that data has been smoothly linked together prior to storage in the memory. As each musical tone is read out, the head data is read out first, followed by the mix data, and then the loop data is read out in alternating directions. The smoothly linked head, mix, and loop portions of the musical tone provide a pleasing reproduction of the original musical tone.

Abstract: A musical sound waveform generator includes a carrier signal generating unit, a modulation signal generating unit, a mixing controlling unit and a waveform outputting unit. The characteristics of the carrier signal from the carrier signal generating unit are determined such that the musical sound waveform generated by the waveform outputting unit is a sine wave or a cosine wave with a single frequency, where the mixing ratio of the modulation signal is made 0 by the mixing controlling unit. Therefore, the mixing controlling unit presets the mixing ratio of the modulation signal to be 0, making it possible to generate a musical sound waveform which is only a sine wave or a cosine wave of a single frequency. During the performance, the mixing ratio can, for example, be determined at a high value immediately after the start of sound generation and thereafter reduced to near 0 with time.

Abstract: A musical tone generating apparatus includes a waveform generator for generating a musical tone signal corresponding to a desired musical tone based on a key-on event which occurs in a keyboard and an envelope generator for generating an envelope which controls the amplitude of the musical tone signal in response to the key-on event. When a key-on event occurs, the envelope generator compares the current value of the envelope with a predetermined value, and based on the result of this comparison, determines a initial value of the next envelope corresponding to the key-on event. Consequently, the musical tone generating apparatus can generate musical tones without generating a click noise even if the key-on event repeatedly occurs over time at short intervals.

Abstract: An electroic musical instrument of the present invention is provided with a damper control as well as tone generation instructin device and tone generation device. While the damper control is operated, the tone generation device continues tone generation even if the stop thereof is instructed by the tone generation instruction device. Moreover there is provided pitch control device adapted to change the pitch of the tone currently generated while the damper control is operated.Accordingly, when the damper control is operated, the resulting musical tones can be enhanced in their variety, distinct from normal tone generation. This allows an electronic musical instrument, for example, to generate such sounds as when the damper pedal is stamped with a piano.

Abstract: A differentiation circuit outputs a normalized time variable signal for each phase. This time variable signal is multiplied by a gain parameter by a multiplier, thus reproducing an AC amplitude level lost in normalization. The reproduced output is added to an amplitude parameter by an adder, thus reproducing a DC amplitude level lost in the normalization. A CPU reads out the parameters of the differentiation circuit and adder from an ROM, and writes them into a parameter memory. When phase-change data is detected, the content of the parameter memory is rewritten, thereby forcibly changing the phase.

Abstract: A detector unit is provided which receives envelope signals related to a predetermined number N of channels to detect a channel showing a greatest or smallest level of the envelope signal among the N channels and outputs data indicative of the detected channel and the level of its envelope signal. When the total number M of the channels is larger than N, a plurality of the detector units are provided, the envelope signals of the number M of the channels are divided into groups numbering not more than N, and the groups are distributed to the respective detector units so that the channel of which level of the envelope signal is the greatest or smallest is detected in each of the detector units. The levels of the envelope signals of the channels detected by the respective detector units are compared with each other, and one detector unit connected with the channel of the greatest or smallest level of the envelope signal is identified.

Abstract: There are provided a tone signal generation circuit capable of selectively generating either a normal tone signal corresponding to a selected tone color or a special tone signal corresponding to the same selected tone color but having a characteristic which is different from that of the normal tone signal, and a tone selection circuit selecting whether the normal tone signal is to be generated or the special tone signal is to be generated in this tone signal generation circuit. A tone signal having a characteristic of a tone generated by a misplay, for example, is used as the special tone signal. In case a tone is generated by depression of a key, the normal tone signal is selectively generated in most cases but the special tone signal may be selectively generated from time to time. By doing so, a tone of a misplay is occasionally generated thereby giving the impression of naturalness as if a natural musical instrument were being played.

Abstract: An electronic musical instrument with a channel assigning device which includes a characteristic information generating unit for generating characteristic information of musical tone envelopes, a sound radiation instructing unit for generating each musical tone selected by a musical tone selecting unit, a processing unit for processing the characteristic information generated by the characteristic information generating unit in response to an elapse of time and an assigned channel determining unit for comparing the results of the processing performed by the processing unit and determining a channel to which the musical tone information should be assigned in response to a sound radiation instruction from the sound radiation instructing unit.

Abstract: A carrier signal generating unit generates a carrier signal. A modulation signal generating unit generates a modulation signal. A mixing controlling unit controls, in mixing the modulation signal with the carrier signal, a mixing ratio of the modulation signal to the carrier signal and outputs a mixed signal in which the modulation signal and the carrier signal are mixed in the controlled mixing ratio. A waveform outputting unit has a predetermined functional relation between its input and output and receives the mixed signal from the mixing controlling unit to provide a modulated musical sound waveform. In this case, the carrier signal and the modulation signal are set such that a desired musical sound waveform is obtained from the waveform outputting unit when the mixing ratio of the modulation signal to the carrier signal is controlled by the mixing controlling unit to a predetermined mixing ratio. And the present invention provides a method of setting the carrier signal and the modulation signal.

Abstract: A tone generating apparatus is provided with the same number of tone signal generating circuits as a polyphonic number, each of which generate multiple tone-component signals having a relatively long tone-ON time and combine the signals to produce a tone signal, and is also provided with the same number of tone signal generating circuits as a predetermined number smaller than the polyphonic number, the latter circuits each generating a tone-component signal having a relatively short tone-ON time. With this arrangement, when tone generation is specified by depression of a key, for example, generation of a musical tone having a relatively long tone-ON time is assigned to one of the former tone signal generating circuits, and, at the same time, generation of a musical tone having a relatively short tone-ON time is assigned to one of the latter tone signal generating circuits, thereby generating a single tone signal.

Abstract: A first musical tone to be generated by a musical tone generating channel and a second musical tone which is the same as the first tone and which already has been generated by another musical tone generating channel are both generated in a superposed manner. When the first tone is generated, the volume of either the first tone or the second tone is superimposed on the generated volume of the other musical tone. Also, the volume attributed to the first musical tone due to decay is reproduced by changing the volume of the second musical tone.

Abstract: An envelope-generating apparatus for an electronic musical instrument is disclosed. The apparatus which generates an envelope signal for a musical tone includes a rate detector for detecting the actual rate-of-change of the envelope signal at an instant before quick-attenuation of the signal is to commence, and a quick-attenuation controller for first setting a predetermined attenuation rate for the envelope signal based on the actual rate-of-change detected by the rate detector and thereafter controlling quick-attenuation of the envelope signal. The apparatus further could include a level detector for detecting an actual envelope signal level at an instant before quick-attenuation commences.

Abstract: A vibration of a string is picked up by a pickup to be converted to an electric signal. A pitch extracting circuit obtains pitch data expressing a pitch or a duration of the string vibration from the electric signal. A musical tone generating circuit generates a musical tone having a corresponding tone pitch in accordance with the pitch data. An envelope extracting circuit extracts an envelope from the electric signal detected by the pickup and supplies a signal expressing the envelope to a multiplier. Furthermore, a signal expressing the musical tone is supplied to the multiplier to be multiplied by the signal expressing the envelope. Thus a musical tone having a controlled envelope determined by the extracted envelope is generated.

Abstract: An electronic musical instrument having a plurality of operators for generating audio frequency waveforms and performing frequency modulation thereof. The operator comprises a wave generator, a phase generator, and an amplitude-envelope generator. The phase generator produces phase-angle data on the basis of frequency-number data modulated by ratio-of-frequency data. While the frequency-number data is common to all operators, ratio-of-frequency data varies independently of those applied to the other operators. This enables operators to create rich, dynamic, lifelike sound. One or more operators are provided with feedback loops that are capable of varying the amount of the feedback in response to key touch, etc., thus achieving expressive tone. A pitch-envelope generator is provided with a random-number generator which modulates the pitch envelope in a random manner to more closely simulate a performance on a real musical instrument.

Abstract: An effect tone generating apparatus can generate an effect tone of an appropriate pattern such as the murmur of a brook or songs of birds, at an arbitrary timing with a simple operation. Since the tone volume of an effect tone can be gradually increased or decreased and the tone volume can be independently controlled in units of channels using a plurality of channels, the audible impressions created by the effect tones can be improved.

Abstract: An envelope shape generator generates envelope shape data for controlling a tone signal in the form of data in decibel representation. In performing a rapid attenuation control called "forcing damp" during attenuation of the envelope shape data generated by the envelope shape generator, the envelope shape data in decibel representation is rapidly attenuated with such a characteristic that inclination of attenuation becomes increasingly steeper. This is advantageous because inclination of a rapidly attenuating portion is modified to a substantially uniform inclination when the envelope shape data is converted to data in linear representation. There are also provided a detection circuit for detecting that the level of the envelope shape has dropped below a predetermined level corresponding to a minimum level at which a tone waveshape can be effectively represented and a circuit for rapidly attenuating the envelope shape in response to this detection. This contributes to elimination of noise.

Abstract: Circuitry for an electronic tone generator effectively isolates a tone modulating RC network from the electroacoustic output device and associated volume control systems. This isolation prevents low or variable impedance of the output portion of the generator from adversely affecting the charge and discharge rate of the RC network. Isolation circuitry includes a MOSFET connected in a source follower circuit to convert the voltage signal from the RC network to a comparable current signal which is amplified through a pair of MOSFETs in a current mirror circuit.