Michael, the "sensitivity" of a microphone doesn't mean what many people would assume that word to mean. The specification simply tells you the amount of electrical signal that the microphone will deliver for a given amount of sound input. Engineers use sensitivity figures to make certain that the signal levels from a microphone will be appropriate for the preamp, mixer or recorder that the microphone will eventually be connected to. A microphone that is too sensitive could overload the input of the next device in the chain when sound levels are high, while a microphone that isn't sensitive enough could force the engineer to set the levels on the preamp, mixer or recorder so high that the input noise would become audible.

That's the issue with "sensitivity." It isn't a measure of the microphone's ability or tendency to pick up low-level background sounds such as room sound. Several different factors control the pickup of room sound, and no one number can predict it--the room itself has a major influence, as well as the character of the noise, and the placement and orientation of the microphone within the room. The polar pattern (directional pickup pattern) of the microphone is fundamentally important, but the details of that pattern can also matter; many microphones that are cardioids at middle (voice) frequencies have a broader pattern at low frequencies, for example.

--best regards