Patent ID: 8457342

Claim:
A differential microphone unit, including a vibration sensing unit having a diaphragm, a stacked substrate on which said vibration sensing unit is mounted, and an upper housing covering said vibration sensing unit and put on one surface of said stacked substrate to form a first space, wherein: said differential microphone unit has a first opening and a second opening provided in an identical surface of said upper housing; a sound wave input from said first opening is transmitted to a front surface of said diaphragm through said first space, and a sound wave input from said second opening is transmitted to a rear surface of said diaphragm through a second space including an internal space of the stacked substrate; said first opening and said second opening are line-symmetric with respect to an axis parallel to a second direction perpendicular to a first direction in which said first opening and said second opening are arranged in said upper housing; a dimension of a width of said first opening and said second opening in a portion parallel to the second direction is longer than a dimension of a width of said first opening and said second opening in a portion parallel to said first direction; a dimension of a width of said second space formed in said upper housing in a portion parallel to said second direction is longer than the dimension of the width of said first opening and said second opening in the portion parallel to said first direction; and the dimension of the width of said first opening and said second opening in the portion parallel to said second direction is substantially equal to the dimension of the width of said second space formed in said upper housing in the portion parallel to said second direction.