On my 2003 ML350 Inspiration Edition with Bose AudioPilot sound, there is a small speaker under the front passenger seat that fires out toward the front passenger door through a grill in the plastic panel covering the seat track at the floor (below the seat adjustment buttons). This speaker is not very substantial, and appears not to be part of the Bose system, which has nine speakers: two in the D-pillars, two in the rear doors, two in the front doors, two in the A-pillars, and the subwoofer under the driver's seat. This speaker is connected to something under the passenger seat. Any ideas?

 

it is for noise canceling. it emmits the road noise out of phase thus cancelling the lower frequencys...

 

I just got an answer from 1-800-FOR-MERCEDES (after a day). It is the Tele-Aid speaker, and is there only on M-Class vehicles. In other models, Tele-Aid uses one of the door speakers, but in the M-Class, a separate speaker under the front passenger seat is provided. The use of Tele-Aid shuts off the V60 phone and mutes the sound system, leaving only this speaker operating.

You learn something new everyday.

 

The noise-canceling idea wouldn't work. The distance between the speaker(s) and everyone's ears needs to be the same. That's why it DOES work for noise-canceling headphones.