Electronic ear plugs

[slik556]

I'm trying to understand, why do people go with muffs or other plugs (like the Surefires) when foam earplugs have a higher NRR? Even the electronic muffs only have NRR numbers in the 20s. The foam plugs I use are rated at 33. I can still hear normal conversation with them in. Please...what am I missing here?

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Oh sorry, take you foam ear plugs out...
No, seriously I sometimes use both plugs and muffs like when shooting high power rifles. But pistols and say 22's I just go with the Surefire Plugs...

[AbbyCat]

I understand that the electronic muffs greatly help in hearing 'normal' sounds and that they block out the 'explosive' loud sounds. I guess my question is...for all the other noises, do they provide enough protection with their lower NRR? How much is enough? Is doubling up the way to go?