Equivalent input noise A
microphone converts
acoustical energy to
electrical energy. Microphones have some level of electrical
noise at their output. This noise may have contributions from random
diaphragm movement,
thermal noise, or a dozen other sources, but those can all be thought of as an imaginary acoustic noise source injecting sound into the (now noiseless) microphone. The units on this noise are no longer
volts, but units of sound pressure (
pascals or
dBSPL), which can be directly compared to the desired sound pressure inputs. This is called
equivalent input noise (EIN), or
input-referred noise (IRN), or
referred-to-input (RTI)
noise.
Input-related interference level A device which uses a
microphone may be susceptible to
electromagnetic interference which causes
sonic artifacts. The problem is not in the microphone, but the interference level can be
related back to the input to compare to the level of typical inputs to see how
audible the artifact is. This is called
input-related interference level (IRIL). ==References==