To be honest, the bluetooth signal should not be dropping.
A few quick questions:
1. Are you near any other interference (i.e. microwaves, and such), because these can cause interruptions in other wireless signals. Hence the interference robustness setting on the Airport card.
2. Maybe more obvious, but are you using the BT within 3 meters of the source? Because BT has a max range of 3 meters before it starts to loose strength and signal.