​Nonlinear, dynamic coupling effects and the manifestation of stochastic resonance are explored in the context of frictional geomaterials. The first experiment is designed to study a single interface between two mineral surfaces. Results demonstrate that as the amplitude of the driving signal approaches the threshold of static frictional resistance, the noise level required to cause slippage decreases and the peak output signal-to-noise ratio increases, inducing stochastic resonance. The second experimental study is conducted with sand specimens. While the classical signature of stochastic resonance is not observed in these multiinterface systems, nonlinear energy coupling effects appear. The effect of signal interaction through the nonlinear behavior of the medium is further studied by simultaneously exciting the specimen with two sinusoidal signals of different frequencies. The output response at the frequency of the primary driving signal increases as the amplitude of the secondary ‘‘noise’’ signal increases. Coupling increases as the driving signal brings the specimen to its nonlinear regime. The results highlight the interaction between friction and vibration in geomaterials, and suggest potential implications to experimental studies, construction operations, and dynamic phenomena such as seismic response and landslides.