Insertion loss class—Enhancing the single number rating system for duct silencers

Abstract

Single number rating systems have been used successfully to select architectural acoustics products for many years. Recently a single number rating system was proposed to evaluate sound attenuators in HVAC applications. The proposed system does not include the very low frequencies. This paper discusses the addition of the 31 Hz octave band to the proposed standard contour for calculating insertion loss class (ILC). A number of examples are shown using actual published silencer test data how the system can be applied to common HVAC noise problems.