The noise in different types of rooms should not exceed the Noise Criterion limits listed below:
Type of Room - Space Type Recommended NC Level
NC Curve Equivalent Sound Level
dBA
Apartments 25-35 35-45
Assembly Halls 25-30 35-40
Churches 30-35 40-45
Courtrooms 30-40 40-50
Factories 40-65 50-75
Hotels/Motels
- Individual rooms or suites 25-35 35-45
- Meeting or banquet rooms 25-35 35-45
- Service and Support Areas 40-45 45-50
- Halls, corridors, lobbies 35-40 50-55
Offices
- Conference rooms 25-30 35-40
- Private 30-35 40-45
- Open-plan areas 35-40 45-50
- Business machines/computers 40-45 50-55
Hospitals and Clinics
- Private rooms 25-30 35-40
- Operating rooms 25-30 35-40
- Wards 30-35 40-45
- Laboratories 35-40 45-50
- Corridors 30-35 40-45
- Public areas 35-40 45-50
Schools
- Lecture and classrooms 25-30 35-40
- Open-plan classrooms 35-40 45-50
Movie motion picture theaters 30-35 40-45
Libraries 35-40 40-50
Legitimate theaters 20-25 30-65
Private Residences 25-35 35-45
Restaurants 40-45 50-55
TV Broadcast studies 15-25 25-35
Recording Studios 15-20 25-30
Concert and recital halls 15-20 25-30
Sport Coliseums 45-55 55-65
Sound broadcasting 15-20 25-30
Example - Estimating NC - Noise Criterion
The Noise Criterion - NC - of a noise spectrum like
62.5 Hz : 40 dB
125 Hz : 50 dB
250 Hz : 55 dB
500 Hz : 60 dB
1000 Hz : 50 dB
2000 Hz : 55 dB
4000 Hz : 45 dB
8000 Hz : 45 dB
