To largely improve directional characteristics when external noises deteriorating the articulation of a hearing aid are eliminated by the direction characteristics of a microphone.

A reception array 5 composed of microphones 1, 2, 3 and 4 having a plurality of channels is arranged on the frame of a spectacle type fixture or a supporting beam for a headphone type fixture. Outputs from each microphone are wavelet-transformed 6 and amplitude and phase spectra are obtained, and the next operation is conducted at every frequency band. Difference is expanded 11 by multiplying phase difference among each channel by an arbitrary coefficient, and amplitude and phase among each channel are interpolated and the number of the channels is multiplied 16 in arbitrary size. These outputs are multiplied 21 by an arbitrary weighting function and phase adjust addition 26 is conducted, and the result is used as a conventional amplifier input by wavelet inverse transformation 27. Phase difference among each channel is expanded, and directional width is reduced by multiplying the number of the channels, and external-noise elimination performance is improved largely.