Thanks, Chana! However, I think it may be illegal in many states to wear earplugs while driving though so it won't always be an option. Do you think, from your own experience, that 8 hours in a car with those readings is safe on your hearing?
Sound level meter readings may be affected by various factors (ie open window, speed etc). Wearing hearing protection in any noisy environment is wise option. For maximum comfort and performance, custom noise plugs may be ordered from an audiologist. Noise Plugs are available in a wide selection for various situations. Different filter levels are chosen for the appropriate attenuation (lowering of noise). Many allow for conversation while filtering out damaging noise levels.