According to the Environmental Protection Agency - EPA - the Day-Night Sound Levels - Ldn - and the Equivalent Sound Level - Leq - should not exceed certain limits to protect public health and welfare.
Values that should not be exceeded:
|Hearing||Leq(24) < 70 dBA||All areas|
|Outdoor activity interference and annoyance||Leq < 55 dBA||Outdoors in residential areas and farms where people spend varying amounts of time in which quiet is a basis for use|
|Outdoor activity interference and annoyance||Leq(24) < 55 dBA||Outdoor areas where people spend limited time such as school yards playgrounds, etc.|
|Indoor activity interference and annoyance||Leq < 45 dBA||Indoor residential areas|
|Indoor activity interference and annoyance||Leq(24) < 45 dBA||Indoor areas with human activities such as schools, etc.|
- Outdoor yearly Ldn levels protect public health and welfare if they do not exceed 55 dB in sensitive areas as residences, schools, hospitals, etc.
- Inside buildings yearly Ldn levels protect public health and welfare if they do not exceed 45 dB.
Note! To protect against hearing damage, one's 24-hour noise exposure at the ear should not exceed 70 dB.
Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.
Age and life expectancy for men and women.
Acceptable noise - dBA - level at typical common locations.
Exposure to noise should be controlled so that it is less than a maximum combination of exposure level and duration.
A noise measurement system for continuous or ambient noise in indoor environments.
An online Preferred Noise Criterion (PNC) calculator.
Background noise frequencies that interferes with speech.
Shift in hearing threshold for men and women vs. age.
The EPA A-weighted sound level day and night equivalent definition - Ldn - for a 24 hour period.
The EPA Equivalent Sound Level - Leq - quantifies the noise environment to a single value of sound level for any desired duration.
Doubling of the distance from a noise source reduces the sound pressure level with 6 decibel.