From time to time high frequency noise emanates from nearby plants and becomes more than just a nuisance to residents; it becomes a public health issue.
Over many years, the LDEQ dismissed this known offsite effect as a local jurisdiction issue, and local officials claimed lack of personnel and lack of monitors to enforce. The plants claim weekend staffing issues.
Currently, local ordinances tend to only address the loudness of noise level measured in decibels and not the pitch or frequency of noise measured in hertz (Hz).
According to the American Hearing Research Foundation " Generally noise induce hearing loss occurs at a pitch of about 2000 - 4000 Hz".
The dangers of high frequency sounds should be addressed by both local officials and the Louisiana DEQ. Both State and Parish officials could develop ordinances to protect the public's hearing. At the very least any noise monitors in the community should include frequency measurements, and those measurements should be posted in real time to a publicly accessible website.
This is an issue the residents of St Bernard have been begging for help with. There is no lack of knowledge of the source of the noise. It is a well documented offsite affect. There seems to be alot of attention on the worker's hearing protection but none for the human beings who reside just on the other side of the fence.
In this article link below, about the Sonic Attack in Cuba, "the incident has brought up questions over how quickly sound waves can cause hearing loss without warning signs.