A new signal-processing technique, spectrum clipping, has been investigated. The spectrum clipper is a passive two-port nonlinear circuit that employs parametric excitation of vibrational modes in a magnetoelastic crystal. Spectrum clipping can be considered as a means of recovering periodic and nearly periodic signals from noise. signal-to-noise ratio (SNR) improvements of up to 30 dB are predicted, the largest improvement occuring for simple sinusoidal signals. Preliminary theoretical and experimental results suggest that spectrum clipping may conceivably provide a low-cost method of interference reduction for domestic communications systems.