A vehicle interior rearview mirror assembly (10) comprises an accessory (24), a reflective element (18) and a bezel (20). The mirror assembly may define portions of a pocket (23) that at least partially receives and secures the accessory therebetween when the reflective element is at least partially received in the bezel. The mirror assembly (110) may include a microphone (124) and an acoustic cover (126) positioned at least partially over one or more inlet ports (124j, 124k) of the microphone. The acoustic cover may include an outer air flow limiting layer (130b) that substantially limits air flow therethrough and a diffusing material (130a) that may space and support the outer layer from the inlet ports to substantially diffuse air flow that penetrates the outer layer. An acoustic barrier (132) may be positioned between a pair of inlet ports of the microphone to enhance the directivity of the microphone.