Noise control in a rectangular duct using active structural panel

In the present work a novel approach for Active Noise Control (ANC) is attempted. A structural panel used as a secondary source for active noise control in a rectangular duct is developed and tested. The structural panel is a square Aluminium trim panel, which is fixed on a steel frame vertically and excited by a electrodynamic exciter. The structural panel has many merits as an acoustic source over traditional loud speakers: it is simple in geometry, lower mass, easy in construction and requires only a simple modification of materials already installed on the duct. The vibration response and acoustic radiation response of the structural panel are studied for a simply supported boundary condition, when panel is subjected to less than 350 Hz harmonic excitation. Real time active noise control experiments are performed in a laboratory using the active structural panel as secondary source. Local attenuation of sound pressure levels of upto 45 dB is realized, in a particular location of the duct when its enclosure was excited by 210 Hz pure tone of harmonic sound.