By trade I am a safety coordinator, so I'm somewhat aware of the dangers of high noise levels. OSHA's limit is 8 hours of exposure to 90db. However, NIOSH recommends an 8 hour exposure of 85 db. I recommend going with the NIOSH recommendation, and that 85db limit will likely be adopted by OSHA at some point in the future as OSHA is often behind the most up-to-date research.
"NIOSH estimates that approximately one in four workers exposed at the 90 dBA OSHA PEL eight hours per day over a 40 year working lifetime will suffer a compensable hearing loss from noise, compared to only about one in twelve workers exposed at the 85 dBA NIOSH REL."
So what about if you're just listening at an hour?
Well, here's a very helpful calculator to give you the TWA, or Time-Weighted Average. https://www.noisemeters.com/apps/exposure-calculator/
Click the standard you wish to use (OSHA's 90db is selected by default, and you can choose the NIOSH or other levels as well).
Type in the sound level, and the exposure time, and it will give you the TWA . You can add multiple listening segments, and it will give you the averaged total at the bottom. (1 hour at 85 db, half hour at 90 db, etc)
A few examples:
1 hour at 95 db is the equivalent of 8 hours at 85 db.
2 hr 30 min at 90 db is the equivalent of 8 hours of 85 db.
By the way, NIOSH has an SPL measuring app for the iPhone, but unfortunately not available on Android (likely because of the inconsistencies of microphone gain from manufacturer to manufacturer).
"NIOSH estimates that approximately one in four workers exposed at the 90 dBA OSHA PEL eight hours per day over a 40 year working lifetime will suffer a compensable hearing loss from noise, compared to only about one in twelve workers exposed at the 85 dBA NIOSH REL."
So what about if you're just listening at an hour?
Well, here's a very helpful calculator to give you the TWA, or Time-Weighted Average. https://www.noisemeters.com/apps/exposure-calculator/
Click the standard you wish to use (OSHA's 90db is selected by default, and you can choose the NIOSH or other levels as well).
Type in the sound level, and the exposure time, and it will give you the TWA . You can add multiple listening segments, and it will give you the averaged total at the bottom. (1 hour at 85 db, half hour at 90 db, etc)
A few examples:
1 hour at 95 db is the equivalent of 8 hours at 85 db.
2 hr 30 min at 90 db is the equivalent of 8 hours of 85 db.
By the way, NIOSH has an SPL measuring app for the iPhone, but unfortunately not available on Android (likely because of the inconsistencies of microphone gain from manufacturer to manufacturer).