Feedforward active structural acoustic control with integrated frequency weighting filter

Abstract

Acoustic comfort is of increasing importance for civil aviation and becomes more challenging to achieve when considering the issues introduced in noise transmission by novel lightweight aircraft structures. Active control systems can offer an effective solution in order to maintain a high acoustic comfort level and are compliant with lightweight aircraft design, as they could complement or even partially replace the weighty and bulky passive damping concepts currently used. Active control systems however traditionally aim at the reduction of the vibration level of a structure or the minimization of the sound pressure level in a given space. These factors cannot be used as reliable indicators for the perceived acoustic comfort, because they do not take into account the aural characteristics of the human ear. Therefore active control systems need to be enhanced so that psychoacoustic aspects of noise are taken into consideration. This paper discusses the development of an active structural acoustic control (ASAC) system with an integrated A-weighted filtering of the acoustic field radiated by a double panel structure. A generic simulation model of a double panel structure with a cavity is used as a representative aircraft structure. The effects of the acoustic filters and the additional A-weighting filter on the broadband control performance of an active feedforward control system are investigated. The A-weighting curve can be used as a simple descriptor for the loudness perception of sound by human hearing and can be considered as a first step towards a more complex psychoacoustic filter that aims at increasing the perceived acoustic comfort.