Given the penchant of so many parishioners to indulge in idle chatter before liturgy, a quiet Bach fugue might actually serve to quiet them. Perhaps this desire to have background music is a reflection of a world now filled with inescapable noise. People are no longer accustomed to silence and immediately respond by filling it with music or conversation.
Putting the tabernacle behind the altar does help, or did in the German church I was in But, then, Germans don't chatter even in restaurants.