*always* wear earplugs while riding.
From
http://www.hearingtestlabs.com/motorcycle.htm
according to OSHA's regulation of industrial noise exposure, an average worker surrounded by levels around 85-90dB for an eight hour day will not exceed the limits of exposure time within a 24 hour period of time.
However, when the sound levels exceed 100dB, your exposure time is reduced to two hours. When sound levels exceed 115dB, your exposure time is drastically reduced to 15 minutes. This puts riding a bike a whole other realm as "wind noise" at highway speeds can measure up to 103dB, or comparable to a running chainsaw. At these levels the rider is not only fatiguing physically from the excess noise exposure, but it also puts him into a position of needing a hearing aid later in life.
I've chosen to use foam shooter's earplugs (available at walmart), inserted as deeply as possible - that gives me 33dB of noise reduction, and it centers in the vocal range, so I'm both well protected and can still hear the engine and traffic nicely.
The best custom-made plugs (
etymotic.com) top out at 25dB reduction, so cheap disposable foam it is for me!
My experience:
5 minutes at highway speed + cheap helmet + no plugs = ears feel painful after
10 minutes at highway speed + cheap helmet + no plugs = I just want to sit in a quiet room for an hour
45 minutes at highway speed + cheap helmet + plugs = just fine
90 minutes at highway speed + cheap helmet + plugs = I just want to sit in a quiet room for an hour
90 minutes at highway speed + good helmet + plugs = just fine
My ears may be more sensitive than most, but the time difference is pretty dramatic, and I still hear everything I need to - it just dials the world down a little.