Evaluation of mechanical background noise outside the norm of generally accepted criteria

Cases are presented where mechanical background noise was found to be acceptable by clients, although it was above the threshold of conventional indoor noise criterion. Other instances are shown where noise levels fell within normal limits but were judged unacceptable. Examples include HVAC noise in offices and residences, chiller and other rooftop equipment noise in multifamily dwellings, and pump noise. Sound quality expectations and the perception of noise sources were found to play an important role in the evaluation of these noise sources.