VENTILATION NOISE—CHARACTERISTICS, EFFECTS, AND SUGGESTED COUNTER-MEASURES
Ventilation is encountered today in practically all types of indoor environments, e. g., in dwellings, leisure facilities, service facilities, schools, hospirals, factories, machine rooms, workshops, stores, offices, vehicles, meeting rooms, teaching areas, restrooms, and control rooms. The problem affects a very large number of people, both at work and during their leisure time. Complaints about ventilation noise have increased in recent years, at the same time as very limited efforts have been made to deal with the problem. The recommendations applicable to ventilation noise usually indicate a maximum acceptable level of 35-40 dB(A). The highest recommended levels are exceeded, however, in many environments.
A .schematic view of a typical central station ventilation system, including a fan, ducts, and diffusers, is given in Fig. 5.59.
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