Microphone sensitivity is usually measured in mV/Pa. If one mic is say 25 mV/Pa and another is 13 mV/Pa how much more sensitive is it in application? How can I figure out how much more gain the mic is actually outputting in dB? I feel like I should know this but I don't.
Sensitivity measures the voltage at the output pins of the mic for a given sound pressure level. 13 mV/Pa means that an air pressure oscillation with an amplitude of 1 pascal (94 dB SPL) at the mic capsule would produce a voltage oscillation with an amplitude of 13 mV at the XLR pins.
Gain is basically the ratio of output level to input level.
In this case we're not talking about an input and output, but you can still talk about the relative gain difference, which would be (25 mV)/(13 mV). The sound pressure level (1 pascal) is the same for both, so it cancels out. The relative gain difference is then 25/13 = 1.9, or about 2x as much voltage for the same pressure.
Thanks for the helpful answer. I also later found this article which was pretty helpful. Check out the table further down the page...