Mysterious Battery Drain

[absdad63]

On three separate occasions over the past two weeks I have been in auditoriums with wireless microphones in use. In each of these instances my battery lost over 50% of its power in just a couple of hours. Is it possible that the A/V equipment is interfering with my phone and causing an extra batter drain? If so, any idea how to stop it? The phone has worked fine on the days that I did not attend a presentation.

HTC Touch running SPB Mobile Shell. Blue tooth turned off.

Thanks.