DE-93-17-3 -- Active Control of Low-Frequency HVAC Fan Noise in Building Systems PDF

Maintains that active noise control is a proven solution to low-frequency noise problems. States an infinite impulse response adaptive filter approach has been used in the application of this technology to the intake and discharge ducts of industrial fans and commercial air handlers. The basic concept is to create an acoustic field equal in amplitude and frequency to the noise acoustic field but opposite in phase. This opposing field cancels the noise field. The outstanding advantage over conventional silencers is superior low-frequency attenuation with negligible flow restriction. Notes additional benefits of the system compared to conventional silencers and explains their operation.

KEYWORDS: Noise control, antisound, fans, buildings.