Voltage From A Microphone.. Correct answer here, just an explanation..?

Question

A microphone is specified as having a sensitivity of -50dBV/Pa. What voltage, in mV, do you expect to get from that microphone when the sound amplitude is 2Pa?

I was shown something like:
–50 dBV = 0.00316 mV
0.00316 mV / Pa x 2 Pa = 0.00632 mV or 6.32 mV
as being the correct answer however I don't see how the .00316 came about from the -50 dBV..
would anyone mind explaining that to me?

mephistowaltz · Accepted Answer

The 0.00316 is just a conversion. Sometimes dBV are used and they express the voltage ratio relative to one Volt. Beware that voltages, because do not express power directly, use a "20" instead of a "10" in their dB formula. To convert dBμV into dBV simply subtract 120. 
 but the following formula is the one you use when dealing with this stuff.

U = (20)* log_10 (u1/u0)
 
     u0, =  {dBV = 1 V ,  dBuV = 1 uV} (these are the limits)

of course to actually convet dBV to V you use the following:

dBV to Volts
V = 10 ^(dBV / 20)

in this case:

V = 10 ^ (-50 / 20) = 0.00316 V

you'll notice that the 0.00316 is in Volts (V) and not milli-volts (mV)

Voltage From A Microphone.. Correct answer here, just an explanation..?

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