What system the voice command can control can depend on the model year. In 2000, it could control the car phone, the radio, and the CD player (if installed) but in 2002 the navigation system was also added to its domain. An original goal of the Linguatronic system was to allow essentially hands-free control of interior systems, especially the car phone by using spoken words.Spoken Multimodal Human-Computer Dialogue in Mobile Environments edited by Wolfgang Minker, Dirk Bühler, Laila Dybkjær This means there is microphone (located in the W220 S-Class) that can listen to the person; one of the issues is hearing the person over background noises and echos. The Linguatronic system used digital pre-processing to support this task. The features is run from hardware in a separate box in the back of the car.
