An automobile digital radio and a cell phone are coupled to provide a hands-free full-duplex speakerphone for the vehicle operator. A digital signal processor and associated apparatus of the digital radio can be used to provide echo-cancellation. The system can be used for both full-duplex communication and for audio performance presentation. The programming capacity of the digital radio automatically inserts an appropriate pass-band algorithm to apply to each type of programming. In addition, dynamic band-pass switching, the digital signal processor detects and mutes the nearest speakers and to further reduce the unwanted sounds and, therefore, improves the full duplex speakerphone performance. The digital signal processor uses an automatic calibration method to determine the nearest speakers, for example playing and recording sounds on each individual speaker and comparing the sound pressure level (SPL) to figure out the closest speakers.