That sounds a bit condescending in someway....... I was in a rush to get to supper so I cut it short.
I don't mean to ruffle any feathers, but if you are buying muffs from princess auto or some such you may want to re-think your spending.
Double up your ear protection, really it does make a differance.
Here is the reason why you shouldn't waste your $$ on muffs with a NRR or 32 or less. According to my 'ear doctor' (I can't for the life of me remeber what their profession is called, I was going to say proctologist..... But that taint right!) The effect of double ear protection is not 'double'. If you have a set of standard foam plugs (usually a NRR of 17 or so generally)and a set of muffs with a NRR of 29 the effective NRR is 31, not 46 as would be reasonable to assume. There is a differance but not much IMHO or my doctors either. If you start with a set of plugs, a good set of rubber re-useable ones the NRR is usually 24. Add to that a set of GOOD quality muffs with a NRR of 33 (35 is the the best I have ever been able to find) and your effective NRR is just about 38. If you step up to a pair of custom fitted plugs from your ear care proffessional the NRR is 29 add to that a pair of good muffs (33 NRR) and you can achieve an effective NRR of 41.
Just FYI a good pair of;
Good rubber plugs will run you $7 to $15
Custom fitted plugs will run you $220+
A good set of muffs (NRR of 33) will run you $80 to $225 (depending on brand)
A good set of electroic muffs with a NRR or 33 will run you $300+
Beware of cheap muffs that claim a NRR or over 28 and cost less than $65. If the deal seems too good to be true it probably is. NRR can be measured several differeant ways. The 'cheaper' muffs will usually use a different scale. ie; muffs from Pricess auto claim a NRR of 30. In actual tests here in Sask at the U of S they achieved a NRR of 19.
Cheers!
***Disclaimer***
The above info is from my healthcare proffessional, if it is flawed please feel free to set me straight. But I do belive everything he told me is/was correct.