Understanding SPL (sound pressure level)

I was recently horrified to learn that the City of Fort Worth is using explosives to scare birds away downtown. I learned this the hard way. With my ears. The city has mounted some sort of sound tube in the back of a pickup truck and city workers drive around blasting innocent people as they try to scare off birds. I know the SPL level of the explosion from a block away is dangerous because my ear nearest the open window of the car is still suffering the effects of the first blast.

How loud is too loud? And how long can you be exposed to a certain SPL before you suffer damage to your ears which would be classified as “Noise Induced Hearing Loss” or “NIHL”?

Here is a diagram I found on the following website that makes things pretty clear: – decibel time exposure guidelines

Decibel Exposure Time Guidelines

If 115db is dangerous after only 30 seconds, what might the acceptable exposure time be for 150+db? None?

Here is a table I found on the following website that lists OSHA guidelines for SPL exposure time guidelines:

permissible exposure time

permissible exposure time

Here is website that shows the expected SPL of various gunfire.

freehearing – SPL levels of gunfire

If I can find the truck doing it’s rounds again, I will take photos and measure SPL. Hopefully more soon…