Toshifumi Kunimoto

Nonlinear function generation apparatus, and musical tone synthesis apparatus utilizing the same

A nonlinear function generation apparatus and a musical tone synthesis apparatus are disclosed. The nonlinear function generation apparatus comprises hysteresis and nonhysteresis function generators for generating hysteresis and nonhysteresis functions using an input signal as a variable respectively, and a multiplier for synthesizing the functions outputted from the generators. The musical tone synthesis apparatus comprises a closed loop including delay circuits, and the nonlinear function generation apparatus.

Wind type tone synthesizer adapted for simulating a conical resonance tube

An acoustic wind instrument having a conical tube is simulated by two cylindrical tubes communicated to each other at each one end. A parallel connection of electrical signal transmission lines, each simulating a cylindrical tube constitute a synthesizer synthesizing the sound of the conical acoustic wind instrument. Each signal transmission line includes a shift register for giving a delay to the input signal, a multiplier for simulating sound reflection, and a filter for affording a tone color. An exciting signal is injected at the interconnection of the parallel connection through a junction circuit.

Brass instrument type tone synthesizer

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.

Musical tone synthesizing apparatus using wave guide synthesis

A musical tone synthesizing apparatus synthesizes musical tones by simulating the tone generation construction of a plucked-string or struck-string instrument. The apparatus has a loop circuit which simulates a vibrating element of the instrument, an excitation circuit creates an excitation signal corresponding to the excitation given to the vibrating element in response to the operation of operators such as a pick or a hammer or the state of the generation body and a memory which stores a non-linear relation between the operator and the vibration element. The excitation signal circulates around the loop circuit and is delayed by means of a delay circuit with a previously determined delay interval, and is fed back into the excitation circuit as the state of the vibrating element. To realize a variety of sounds depending upon characteristics of the operator, such as the shape and hardness of the pick or the hardness of the hammer, a readout value of the memory, which is read out according to such characteristics, is supplied to the loop circuit.

Device for synthesizing a musical tone employing random modulation of a wave form signal

An apparatus for synthesizing a musical tone comprises a loop circuit for circulating an input wave form signal through a delay circuit, a wave form memory, and a random modulation circuit for modulating the wave form signal stored in the wave form memory. The random modulation circuit generates a random signal, such as a noise signal. The random signal modulates address data to the wave form memory, so that the read wave form data read out from the wave form memory is delicately varied with time.

Multi-stage spectral subtraction for enhancement of audio signals

This paper describes a technique based on spectral subtraction (SS) for enhancing audio signals which have nonstationary properties. In the technique, audio signals are modeled as a sum of sinusoidal components, which are called tones, of various frequencies and durations. We show that the analysis window length for SS should be adjusted in accordance with the tone duration to obtain higher performance on SS. Then we propose a multi-stage SS approach into which an appropriate window length selection mechanism is incorporated. We also propose a technique for suppressing an artifact called pre-echo which appears in the noise reduction process. It is shown from the result of a subjective evaluation test that the proposed technique gives superior performance to the conventional SS for enhancement of audio signals including speech, piano, drums, and orchestra.

Musical tone waveform signal generating apparatus using a plurality of non-linear converters

A musical tone waveform signal generating apparatus in which a waveform signal is circulated to generate a musical tone waveform signal. The apparatus includes an excitation portion for mixing an excitation control signal with the waveform signal and for non-linearly converting the mixed waveform signal and a signal transmission portion coupled with the excitation portion to feed back the converted waveform signal to the excitation portion with delay of a predetermined time for causing on the converted waveform signal a resonance frequency corresponding with a pitch of a musical tone to be generated. In the excitation portion, the non-linear conversion of the mixed waveform signal is effected by a plurality of non-linear tables to generate various kinds of musical tone waveform signals, and the converted waveform signal is controlled by a tone color control signal to simulate the musical tone as a natural musical tone created by performance of a musical instrument such as a wind instrument, a brass-wind instrument, a stringed instrument or the like.

ARMA digital filter design method for audio and musical purposes

Approximation methods of ARMA (AutoRegressive Moving-Average) Digital Filters having arbitrary frequency-magnitude response and their applications to the areas of audio signal processing and music synthesis are discussed. Although many approximation methods in this direction have been investigated and proposed around 1980, practical techniques to apply these methods onto the above areas have not been investigated well. A transpose mean of transfer functions of ARMA digital filters to improve application to the audio-band signal is proposed and discussed.

The VL1 virtual acoustic synthesizer

McIntyre et al. [J. Acoust. Soc. Am. (1983)] suggested the idea of constructing electrical musical instruments based on physical models of natural musical instruments. The first product employing such an approach has been developed, the VL1, and the synthesis technique is called ‘‘virtual acoustic synthesis.’’ Differences and comparisons between conventional music synthesizers and the virtual acoustic synthesizer will be shown. Also, problems arising in the approximation of natural musical instruments and the realization of approximated models will be described to some extent. The VL1 synthesizer also contains a sound effects section and other common features found in commercial digital musical instruments. The system is realized using specialized DSP chips. The current VL/virtual acoustic synthesizer is expensive, so reducing the cost was the next goal. A low‐cost version, the VL70‐m, was also released this year. There will be a small demonstration to exhibit the sound of the instrument.