Measurements of the BNE in a partially evacuated container yield rise times that can be considerably reduced from the rise times for the same intruders at normal atmospheric pressure. The rise rates of the intruders that are slowest under normal atmospheric conditions are significantly sped up when the pressure is lowered, indicating that the effects of air in the spaces between particles making up the granular bed cannot be ignored in treating the dynamics of the bed and the intruder. The results of simulations of the effects of air flow on the motion of a shaken granular bed indicate that this influence cannot be neglected in identifying the physical causes of the BNE.