An analytical model of a thin, flexible shell is evaluated to study the mechanisms of interior sound reduction by active control of the shell vibrational response. A single exterior acoustic monopole is used as the noise source while the secondary controller is represented as a single point force applied directly to the shell wall. The complex amplitude of the acoustic monopole is specified a priori, however, the complex amplitude of the point controller is initially unknown. The control force amplitude is evaluated such that the line-weighted mean square pressure is minimized along the shell wall in the excitation plane. The active control model is evaluated for harmonic excitation. Results indicate spatially averaged noise reductions in excess of 20 dB over the source plane for acoustic resonant conditions within the cavity. Modal response of the shell and the coupled interior pressure field indicate substantial control spillover in the shell due to control force excitation; however, control spillover is predominately constrained to the shell and thus does not contaminate the contained acoustic field.
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