Abstract: A speech processing apparatus for obtaining a processed speech which is natural and comfortable for a listener, by refining a gain value assigned for each frequency band in enhancing formants in a power spectrum. The power spectrum, calculated in a frequency analyzing unit, is subject to contrast enhancement in a contrast enhancing unit, and judged as to whether it is a format or not in each frequency band. In a gain value assigning unit, a gain value of 1 is assigned to a formant, and a gain value smaller than 1 is to a frequency other than formant. A threshold value for each frequency band is determined by a threshold value determining unit in accordance with power spectrum of input speech signal, to eliminate the effect of variation in speech level.

Abstract: In an apparatus for speech signal processing, first a coefficient calculation is performed to determine a value for suppressing a change of level of an input signal. Next, an input signal delay is performed to delay the input signal by a time required for the coefficient calculation. Then an output of the input signal delay is multiplied by the value obtained by the coefficient calculation, thereby obtaining an output signal.

Abstract: The adjustment of a noise suppressing apparatus inputs the voice signal with the noises being piled up in it to decide the weight coefficient of the neutral network 130 with a back propagating method so that the errors of the output signal and of the noiseless signal may become minimum, the noise suppressing apparatus where noises in a voice signal are suppressed even in a situation where the positional relation between the noise source and the voice source may often change, and noises offensive to the voice after the noise suppression may not remain, the suppressing effect is not deteriorated even if the time pattern of the input signal is varied.

Abstract: A feedback type microwave oscillator using a three-terminal active element employs both series feedback and parallel feedback and capacitance in its output circuit, thereby increasing the small signal negative resistance, and the output power and its resistance to impedance fluctuations of a load attached thereto.

Abstract: A dielectric resonator microwave oscillator in which the gate of a FET is connected to a resonance circuit. An inductor is connected to the drain of the FET, and the output is taken from the source of the FET. This dielectric resonator microwave oscillator has enhanced negative resistance and positively starts the oscillation even when there is a low reflection coefficient of the resonance circuit. Using a circuit which consists of a capacitor and inductor between the source and the output terminal, a further increasing of negative resistance at the gate of the FET is obtained.