A system for cancelling or attenuating noise in at least two positive displacement compressors proximately located from each other for use with a heating or cooling system. A lead compressor and a lag compressor have a controllable rotational speed and phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at substantially the same speed for each compressor, with a phase-lock loop and a comparator circuit for each compressor. The controller controls the phase of operation of the compressors through an oscillator so that the lead and lag compressor pressure pulses are spaced between successive outlet pressure pulses to effectively double the combined pulsation frequency for noise attenuation.