Abstract: The disclosure is directed to a steady state signal noise eliminator generally used with fire-fighting equipment including a pair of capacitance and resistance circuits series connected to the input having output signals representative of noise that is phase shifted with respect to the audible signal and is applied to a pair of operational amplifiers connected to the phase-shifting circuits and having their outputs connected to an emitter follower for summing the signals received. A voltage divider is connected to the inputs of the phase-shifting circuits and is connected to a difference amplifier having inputs connected between the voltage divider and an emitter follower to provide an output signal in which only the audible sounds without interference are connected to the output.