The intrinsic noise of any audio device or other electronic system, generally measured in dBm. Sometimes the noise floor is measured in terms of RMS voltage rather than power, and this makes sense in the case of devices such as voltage amplifiers or tape recorders. Includes Johnson noise and flicker noise. See quiescent noise. To calculate the intrinsic noise level of a device, expressed in watts: if one took one 600Ω resistor on the input of a (noiseless) microphone preamp with a 60dB gain, the output would be about -100dBm. This is the lowest possible noise floor:
