Active noise control using DSP: Experimental activities on advanced aircraft windows

Abstract

Aircraft windows are a significant path for structure-borne and air-borne noise transmission in aircraft. Turbulent Boundary Layer noise is mainly transmitted into aircraft cabin by airborne paths, but structure-borne noise, associated with engine vibration, and interactions between aerodynamic wakes and aircraft structure, make a significant contribution to interior noise levels, especially at certain discrete frequencies. The heavy sidewall treatments, typically located behind the sidewall trim panels to reduce the amount of noise and vibration due to external sources, do not ensure an effective solution for cabin noise reduction if windows provide a weak link in noise transmission.
In this paper, an active noise control system applied to a triple-pane aircraft window prototype is presented. Piezo stacks actuators are integrated into the prototype to drive the system generating sound waves counteracting the primary noise to be canceled in a specific area (quiet zone). A suitable control algorithm based on a feed-forward strategy is developed and tested in a digital control system running in a DSP control board. The effectiveness of the proposed control architecture is validated by real-time experiments addressing the acoustic control of a reference enclosure subjected to tonal and narrow-band noise disturbances.