Bombardier make turbo-prop aircraft in their Q-series that have an active noise and vibration control system to reduce the noise level inside the cabin. Their Noise and Vibration Suppression System (NVS) uses actively controlled tuned vibration absorbers attached to the fuselage to reduce the vibration, and hence reduces the noise transmitted into the cabin. The system was designed by Ultra-electronics.
Read more on the Bombardier web site.