Experiments on reduction of aircraft interior noise using active control of fuselage vibration

Abstract

Interior sound in aircraft fuselages is directly coupled to fuselage vibration. This suggests the use of active vibration control of the fuselage vibration to reduce interior noise levels. In this paper, preliminary experiments to investigate this new technique are discussed. The experiments were performed on a closed cylindrical shell excited by an external acoustic source, representative of an aircraft fuselage. Active vibration control of the shell was achieved by a single minishaker attached pointwise to the exterior wall of the cylinder. Sound levels throughout the cylinder were measured by a moveable microphone traverse. The interior levels were found to be attenuated at most locations between 10 and 35 dB by the active vibration control with a constant control amplitude and phase, i.e., global attenuation was achieved. The physical mechanisms behind the effect are discussed. The new method shows much potential for reduction of propeller interior noise in aircraft, without the penalty of large added weight.