A removable case for an electronic device may have an acoustic isolation mechanism between the removable case and an acoustic component on the electronic device. The acoustic isolation mechanism may be a compressible component that may provide an acoustic seal between an inner surface of the removable case and an exterior surface of the electronic device, and may include a waterproof acoustic membrane. The waterproof membrane prevents the entry of water while reacting to sound pressure changes to acoustically couple the electronic device with sounds outside the case. The acoustic isolation mechanism may be constructed of several different materials and several different manufacturing processes.