Microphone sensitivity becomes a topic of discussion as soon as it becomes a problem.
I’d hazard a guess that most people don’t think about microphone sensitivity until the moment when a microphone picks up a sound that explodes out of the house speakers, to which someone says, “that microphone’s really hot!”
Microphone sensitivity is the measure of the microphone’s ability for converting acoustic pressure into an electric voltage. The higher the sensitivity, the less amplification required to bring the sound to a useable level on the mixer channel. The lower the sensitivity, the greater the amplification required.
Talking about amplification is in the area of the mixer’s pre-amplifier. This pre-amp boosts the signal coming into the mixer. Depending on your mixer, it will be called by different names such as head amp or pre-amp.
Microphones which appear significantly more sensitive than others, in the signal chain, are thought of as “hot” or as a “hotter” microphone.
Digging Into The Details
Sensitivity is measured against a specific baseline in a specific way. That is to say, it’s measured against a specific sound level, on-axis to the microphone, in a free sound field.
Even more specifically, the microphone sensitivity is based on a 1 kHz frequency at 94 dB SPL. Specifically speaking, that is.
The measurement of acoustic pressure converted into electric energy is listed in two ways. It can be listed as milli-volts (mV) produced per Pascal unit It can also be declared as dBV per Pascal unit.
Don’t worry too much about the new “Pascal unit” terminology—it is the unit for pressure and in this case, it’s a constant of 94 dB SPL.