Tham khảo tài liệu 'noise and vibration control episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TM 5-805-4 AFJMAN 32-1090 Table 2-1. Category Classification and Suggested Noise Criterion Range for Intruding Steady-State Noise as Heard in Various Indoor Functional Activity Areas. Category Area and Acoustic Requirements Noise Criteriona 1 Bedrooms sleeping quarters hospitals residences apartments hotels motels etc. for sleeping resting relaxing . NC-20 to NC-30 2 Auditoriums theaters large meeting rooms large conference rooms radio studios churches chapels etc. for very good listening conditions . NC-15 to NC-30 3 Private offices small conference rooms classrooms libraries etc. for good listening conditions . NC-30 to NC-35 4 Large offices reception areas retail shops and stores cafeterias restaurants etc. for fair listening conditions . NC-35 to NC-40 5 Lobbies drafting and engineering rooms laboratory work spaces maintenance shops such as for electrical equipment etc. for moderately fair listening conditions . NC-40 to NC-50 6 Kitchens laundries shops garages machinery spaces power plant control rooms etc. for minimum acceptable speech communication no risk of hearing damage . NC-45 to NC-65 the sound level criteria should be even lower than the criteria normally considered applicable. This criteria given above is intended to be illustrative any occupied or habitable area not identified in the list can be assigned to one of these categories on the basis of similarity to the types of areas already listed. Generally where a range of criteria is given the lower values should be used for the more critical spaces in the category and for nonmilitary areas outside the control of the facility the higher of the range of criteria may be used for the less critical spaces in the category. Certain short-term infrequent sounds such as the weekly testing of a fire pump or an emergency power generator may be allowed to exceed normal criteria in relatively noncritical areas as long as the normal functions of these areas are not seriously restricted by the increase in noise. .
