World Health Organization's Noise Criteria
The following is a list of noise and acoustical figures recommended by the World Health Organization. The figures are the maximum recommended, except otherwise noted. Find below the explanation of the abbreviations.
| Limits | Effect if exceeded |
| 100 - 130 dBA | Auditory disconfort |
| 130 - 140 dBA | Physical damage risk (e.g., ear drum rupture) |
| 130 dBA | Acute pain |
| 70 dBA Leq24 | Negligible hearing impairment |
| 30 dBA Leq | Excellent intelligibility |
| 45 dBA Leq | Complete intelligibility |
| 40 - 55 dBA Leq | Reasonably good intelligibility |
| < 0.6 s Trev | Adequate intelligibility |
| 0.25 - 0.5 s Trev | Adequate intelligibility for the hearing impaired |
| S/N > 0 dB | Speech comprehension |
| S/N > 10 dB - 15 dB | Speech comprehension for foreign languages, complicated messages |
| 100 dBA Leq4 | Concerts |
| 90 dBA Leq4 | Discotheques |
| 140 dB peak | Impulsive sounds |
| ASPL < 80 dBA | Toys, at child's ear |
| CSPL < 130 dBC | Toys, at child's ear |
| 30 dBA Leq | Interior noise while sleeping |
| 40 - 45 dBA Lmax (fast) | Noisy isolated events while sleeping |
| 45 dBA Leq | Exterior noise while sleeping (open windows, assuming 15 dB reduction) |
| 35 dBA Leq | Hospital rooms |
| 45 dBA Lmax (fast) | Noisy isolated events, Hospital rooms |
| 50 - 55 dBA Leq | Outdoors, daytime |
| 40 - 50 dBA Leq | Outdoors, nighttime |
| 1 s Trev | School bars |
| 55 dBA Leq | School patios |
| If LeqC - LeqA > 10 dBA and LeqA < 60 dBA | Add 5 dBA to LeqA |
| If LeqC - LeqA > 10 dBA and LeqA > 60 dBA | Add 3 dBA to LeqA |
Abbreviations
Leq: Equivalent level during measurement
Leq24: Equivalent level extended to a 24 hour period of time
Leq4: Equivalent level extended to a 4 hour period of time
LeqA: Equivalent level with an A frequency weighting
LeqC: Equivalent level with a C frequency weighting
Lmax: Maximum time weighted level (fast, slow, impulse)
Peak: Maximum instantaneous level
fast: .125 s time weighting
slow: 1 s time weighting
SPL: Sound presure level
dBA: Decibel with an A frequency weighting
dBC: Decibel with a C frequency weighting
S/N: Signal to noise ratio, usually in decibels
Trev: Reverberation time (how long lasts sound after turning its source off)
This information was taken from the book on Community Noise edited by Berglund and Lindvall, published by the Karolinska Institute, Sweden, which is available from the Stockholm University.