Noise Criterion vs. Noise Rating and dB(A)
Comparing Noise Criterion (NC, NCB, RNC) to Noise Rating (NR) and dB(A).
Noise Criterion - NC - were established in U.S. for rating indoor noise, noise from air-conditioning equipment etc.
In Europe it is common to use Noise Rating Curves - NR.
dB(A) - LA - is a weighted method compensating for the human hearing of sound pressure at different frequencies.
Choosing appropriate noise criteria is important when specifying acceptable levels of noise. Most organizations use a particular index based upon practical experience. Recommended maximum noise levels for different types of rooms and standards are indicated in the table below
| Type of Room - Occupancy | Maximum Level (dB) | ||||
|---|---|---|---|---|---|
| Noise Criterion - NC, NCB, RNC - | Noise Rating - NR - | dB(A) | RC | ||
| Very quiet | Concert and opera halls, recording studios, theaters, etc. | 10 - 20 | 20 | 25 - 30 | 20 |
| Private bedrooms, live theaters, television and radio studios, conference and lecture rooms, cathedrals and large churches, libraries, etc. | 20 - 25 | 25 | 25 - 30 | 25 | |
| Private living rooms, board rooms, conference and lecture rooms, hotel bedrooms | 30 - 40 | 30 | 30 - 35 | 30 | |
| Quiet | Public rooms in hotels, small offices classrooms, courtrooms | 30 - 40 | 35 | 40 - 45 | 35 |
| Moderate noisy | Drawing offices, toilets, bathrooms, reception areas, lobbies, corridors, department stores, etc. | 35 - 45 | 40 | 45 - 55 | 40 |
| Noisy | Kitchens in hospitals and hotels, laundry rooms, computer rooms, canteens, supermarkets, office landscape, etc. | 40 - 50 | 45 | 45 - 55 | 45 |
