A method of attenuating the sound emanating from a bank of a plurality of vibrating screens of a plurality of vibrating screening machines including the steps of providing a master pulse of known phase and frequency, comparing the phase and frequency of a plurality of vibrating screens with the known phase and frequency of said master pulse, and adjusting the phase and frequency of said bank of plurality of vibrating screens so that the waveforms produced thereby tend to cancel each other. An apparatus for implementing the method is also disclosed.