An electronic device having a composite acoustic membrane to inhibit water ingress and to allow sound transmission, is disclosed. Embodiments include an electroacoustic transducer within an encased space of a casing, and a composite acoustic membrane between the electroacoustic transducer and an acoustic port in the casing. The acoustic membrane may include a nonporous region at least partly covering the acoustic port, and a porous region to vent the electroacoustic transducer volume to the encased space and/or to an environment surrounding the casing. Other embodiments are also described and claimed.