Study On Active Noise Control Of Structure-borne Sound In Enclosed Space

The active noise control (ANC) of enclosed sound field has long been an attractive task in the field of modern noise control, especially the active control of structure-borne noise has practical value.Firstly, the thesis is concerned with the effectiveness of active noise control inside a rectangular enclosure with six rigid walls under the potential energy minimization (PEM), squared pressure minimization (SPM) and energy density minimization (EDM) control algorithms. The location of error sensors is also studied. The thesis extends the study of active noise control with visualization of sound fields.According to modal superposition theory, the modal responses of structure and sound pressure for a structural-acoustic coupled system are established by combining their own Green function. These two formulas are the essential basis for the analysis of structural-acoustic coupling of enclosure. Optimized control models under PEM SPM EDM control algorithms are obtained. The control mechanism of a panel-cavity system using a point force is analyzed by another method.Both global and local effects of active noise control inside a plate-cavity system are analyzed. For global control, the performances of active noise control using a point force, a point acoustic and combined control source are studied. For local control, using a point acoustic source, the performances of active noise control under three control algorithms, namely PEM, SPM and EDM are compared. Also, the location of error sensors is studied. The thesis extends the study of active noise control with visualization of sound fields. The effectiveness of active noise control using dual error sensors is analyzed.Combining finite element method and modal coupling theory, a new modeling method is developed for active minimization of noise within a three-dimensional irregular enclosure.At last, in order to demonstrate the validity of the modal coupling and...