That's not entirely true, if you're selectively lowering the volume of different frequencies it might solve the problem. The only problem with that is that ear

That's not entirely true, if you're selectively lowering the volume of different frequencies it might solve the problem. The only problem with that is that earplugs tend to reduce high frequencies more than low frequencies, but background noise is mostly low frequencies. Earplugs might help you hear people in a machine shop with a lot of high frequency noises though.