An acoustically permeable material is disposed within an aperture of an electronic device to provide aesthetic appeal for the electronic device and protection for an acoustic device mounted within the electronic device. A stiffener is used in conjunction with the acoustically permeable material to improve its ability to resist permanent mechanical deformation from external forces. In some embodiments the stiffener may have multiple cavities enabling improved isolation between multiple acoustic devices within the same aperture. Other methods of employing acoustically permeable materials are disclosed that improve the aesthetic appeal, acoustic performance and/or manufacturability of the electronic device.