Understanding microphone specifications can help in selecting a model suitable for any particular application.
One of these specs is sensitivity. This the open circuit voltage at the output of the mic for a given sound pressure level at the mic element. This value is usually expressed as mV/Pa (millivolts per Pascal), usually at 1kHz. One Pascal (Pa) is equal to 94 dB-SPL (sound pressure level). The voltage is also often converted into a decibel level relative to one volt (dBV).
A typical sensitivity value for a dynamic handheld mic is 2.5 mV/Pa or -52 dBV. This is good for a situation where a person speaks close into the mic. For singers and people who can project, this kind of mic could be worked a few inches away from the mouth, but wouldn’t be a good choice for trying to pick up the voice of an average or quiet speaker from a foot or two away. In the last case, the voltage output from the mic could easily fall below -60dBV, below the amplifying ability of many mic preamps to bring the signal up to line operating level.
For a handheld condenser mic a typical sensitivity value could be 4 mV/Pa or -48 dBV. This mic will allow you a little more distance from a talker than the first example.
At the other extreme, one particular shotgun mic, which is designed to pick up sounds from a distance, has a sensitivity rating of 50 mV/Pa or -26 dBV. With this type of mic, at about 16 feet from a person speaking at a sound pressure level of 94 dB, the mic will output around -56 dBV, still within the “range” of a good mic preamp.
Of course sensitivity is just one parameter to consider in choosing a mic, but this spec can give some indication of intended use. No spec, however, can replace good listening tests.
