ABSTRACT
Low frequency noise poses a problem in many situations. The use of large panels, such as structural components in transport vehicles, buildings etc., can result in significant noise since they often have natural frequencies below 100Hz. Particular problems arise when resonance frequencies lie in the infrasonic range (natural frequencies below 30Hz) since external excitations can couple with these low natural frequencies to increase the amplitude of vibration, causing discomfort and fatigue. The use o f traditional protection systems such as ear muffs, conventional active noise reduction, attenuating materials and insulators are not always feasible, or are inefficient in this frequency range. Active structural control using ‘Smart’ Structures therefore becomes attractive.
