Patent ID: 8107652

Claim:
An omnidirectional electret condenser microphone element comprising: an electrically conductive casing, wherein said electrically conductive casing has a first end portion and a second end portion, wherein said first end portion is comprised of at least one acoustic aperture; a circuit board disposed within said casing and closing an opening at said second end portion of said electrically conductive casing; a diaphragm disposed within said electrically conductive casing, wherein a first surface of said diaphragm is outwardly directed towards said at least one acoustic aperture and wherein a second surface of said diaphragm is inwardly directed towards said circuit board; a spacer interposed between said diaphragm and said circuit board; an acoustic cavity formed within said electrically conductive casing, wherein said acoustic cavity is at least partially defined by said second surface of said diaphragm, said circuit board, and said spacer; and at least a first air passageway and a second air passageway, wherein said first and second air passageways are in acoustic series, said at least first and second air passageways coupling said at least one acoustic aperture to said acoustic cavity formed within said electrically conductive casing, wherein at least one of said first and second air passageways provide an acoustic roll-off of at least 2.0 dB between 300 Hz and 100 Hz.