ADAPTIVE NOISE REDUCTION TYPE VOICE INPUT DEVICE

摘要

PURPOSE:To prevent a desired voice from being reduced and reduces only an object unnecessary sound in an adaptive noise reduction type voice input device. CONSTITUTION:A microphone 21 for reference input which generates output signals of two mutually opposite phases corresponding to a voice input direction is arranged so that the voice input direction wherein an output signal having the opposite phase from the output signal of a microphone for main input for collecting the desired voice is obtained matches the arrival direction of the desired voice. A signal approximating an unnecessary signal is generated by an adaptive filter 24 from the voice signal from the microphone for reference input and subtracted by a subtracting means 15 from the voice signal from the microphone for main input. The adaptive filter 24 is so adjusted as to minimize the output power of the subtracting means 15, and the operation of the adaptive filter means 24 is so limited that a weighting coefficient Wk supplied to a coefficient multiplier satisfies Wk>=0 at all times.