Acoustic vents are engineered to allow sound to travel through at an optimal level, without allowing outside elements into the device. Usually constructed with performance materials like Gore's ePTFE (expanded polytetrafluoroethylene) membrane, the above-average air permeability and water resistance assist in keeping water and dust from entering while still allowing for acoustics. Depending on the needs of the device such as size, shape & level of protection they can be tailored to suit various applications.