A brief social history of active noise control in ducts

Abstract

Considerable progess has been made in the applicaiton of active noise control in ducts since the pioneering work by Lueg over 60 years ago. These developments will be briefly reviewed with special emphasis on three remaining technical challenges including inadequate transducer output power and signal coherence at frequencies below about 50–100 Hz and high modal content at frequencies above about 500–1000 Hz. Although the potential for improvement remains significant, some problems may be approaching fundamental physical limits. However, widespread application may be more restricted by various social and commercial issues. Among these are the relatively low value that is often placed on noise control and energy savings, the lack of an adequate infrastructure to supply and maintain active noise control systems, and the cultural and business changes required to apply a technology that requires system design, easily demonstrates its performance, and often reveals the noise level of the source. Technological similarities between ANC systems and electronic security systems will be discussed. Social-cultural similarities between these systems and a weapon of warfare, the machine gun, will also be considered [John Ellis, The Social History of the Machine Gun (The Johns Hopkins University Press, Baltimore, 1975)].