The microphone system of the invention executes an adaptive filter
processing by using output signals from two microphones to output a
speaker's voice signal with an improved SN ratio, in which the two
microphones are laid out close to each other, and the angles formed by
the orientations of the microphones with respect to the speaker's
vocalizing direction are made different for each of the microphones. For
example, the microphones are mounted on the sun visor of a vehicle, or on
the ceiling above the front passenger seat or the driver's seat of the
vehicle, with the orientations of the microphones differentiated.
Further, the SN ratio of the output signal from one microphone is raised,
and the SN ratio of the output signal from the other microphone is
lowered. For example, one microphone is positioned right above a
speaker's face, and the other microphone is spaced apart on the occipital
side by about 1 to 5 cm from the position of the first microphone. Thus,
the microphone system improves the SN ratio of the voice signal.