15 April 2024
What Are Noise Rating Levels?
By Elta
15 April 2024
Noise Rating Levels or NR Level Curves are developed by the International Organization for Standardization (ISO) and specify an indoor acoustic environment for different requirements of hearing preservation, speech communication and annoyance, in different applications.
Noise Rating values for different sound pressure levels are tabulated below and are the established sound pressure levels at different frequencies. Noise Ratings are then used to specify the maximum permissable sound power level at each frequency by selecting a single Noise Rating (NR) number. The use of Noise Rating – NR – is widespread across Europe.
Noise Criterion or NC levels are a different set of values developed for the same purpose, the use of Noise Criterion (NC) is mainly used in North America.
Noise Rating Values (dB)
NR Level | 63 HZ | 125 HZ | 250 HZ | 500 HZ | 1000 HZ | 2000 HZ | 4000 HZ | 8000 HZ |
---|---|---|---|---|---|---|---|---|
NR 20 | 51 | 39 | 31 | 24 | 20 | 17 | 14 | 13 |
NR 25 | 55 | 44 | 35 | 29 | 25 | 22 | 20 | 18 |
NR 30 | 59 | 48 | 40 | 34 | 30 | 27 | 20 | 18 |
NR 35 | 63 | 52 | 45 | 39 | 35 | 32 | 30 | 28 |
NR 40 | 67 | 57 | 49 | 44 | 40 | 37 | 35 | 33 |
NR 45 | 71 | 61 | 54 | 48 | 45 | 42 | 40 | 38 |
NR 50 | 75 | 65 | 59 | 53 | 50 | 47 | 45 | 43 |
NR 55 | 79 | 70 | 63 | 58 | 55 | 52 | 50 | 49 |
NR 60 | 83 | 74 | 68 | 63 | 60 | 57 | 55 | 54 |
NR 65 | 87 | 78 | 72 | 68 | 65 | 62 | 61 | 59 |
NR 70 | 91 | 83 | 77 | 73 | 70 | 68 | 66 | 64 |
NR 75 | 95 | 87 | 82 | 78 | 75 | 72 | 71 | 69 |
NR 80 | 99 | 91 | 86 | 82 | 80 | 78 | 76 | 74 |
Recommended Noise Ratings
The table indicates recommended Noise Rating specifications for some common interior room applications.
For advice on how to specify or achieve the recommendations please contact us.
Room Application | NR Level | Room Application | NR Level |
---|---|---|---|
Sound, Broadcast & Recording Studio | 20 | Reception | 30-35 |
Concert Hall | 20-25 | Open Plan | 35 |
Lecture Theatre, Cinema | 25-30 | Assembly Hall | 25-35 |
Operating Theatre | 30-35 | Library, Museum | 30-35 |
Multi Bed Ward | 35 | Wash Room, Toilet | 35-45 |
Wash Room, Kitchen | 35-40 | Swimming Pool / Sports Arena | 40-45 |
Individual Room | 20-30 | Garage / Car Park | 55 |
Ballroom, Banquet Room | 30-35 | Church | 25-30 |
Corridor, Lobby | 35-40 | Classroom & Lecture Theatre | 25-35 |
Kitchen | 40-45 | Laboratory | 35-40 |
Restaurant | 35-40 | Warehouse & Garage | 45-50 |
Night Club, Public House, Cafe | 35-40 | Workshop | 50-65 |
Large Retail Space, Supermarket | 40-45 | Bedroom | 25 |
Boardroom, Single Office | 25-30 | Living Room | 30 |