A digital sound processor is provided to enhance the vocal to non-vocal noise ratio of the signal processed by a vehicle audio system such as a cellular telephone, emergency communication device, or other audio device. Optionally, an indicator (72) is provided for use with the vehicular audio system in order to provide a user of the audio system with a status signal relating to a reception quality of a vocal signal from the user. The microphone (18) of the audio system may be mounted within an accessory module (10), which may be mounted to an interior surface of a vehicle windshield (12). The accessory module (10) provides a fixed orientation of the microphone (18) and is easily installed to the vehicle as it is manufactured or as an aftermarket device. The indicator (72) may be mounted at the accessory module (10) or elsewhere at the mirror assembly.