Internal vent structure for waterproof microphone acoustic cavity

A method and apparatus are described for providing an acoustically-resistive air-permeable venting structure (117) within a sealed microphone (105) acoustic cavity. A microphone (105) is mounted on a printed circuit board (103) and positioned within a housing (101). A water-resistant membrane (111) seals the microphone (105) from an exterior of the housing (101), and an active acoustic cavity establishes an acoustical connection between the water-resistant membrane (111) and the microphone (105). An acoustically-resistive air-permeable venting structure (117) is formed in the body of the printed circuit board (103) and connects to the active acoustic cavity either directly or via a separate vent path. The venting structure (117) provides a viscous dampening effect by venting an active acoustic cavity of the electronic device (100) to the rest of the enclosure sealed by the water-resistant membrane (111).