Reysc wrote:AggieMM wrote:I've been looking at this one (on-line). Seems too good to be true, 27dB rating for $35.00.
Item:QT-227184
Just haven't had time to get to Cabelas to double check the on-line claims.
Ryan
I ordered a pair just now. As I said I would like to get a basic first and go from there.. I'm not into match shooting yet so I guess it will work for now. I got it 2 day Priority ( does UPS deliver Saturday) so hopefully I can try it out on Monday...
Ryan,
This is the exact same unit sold by Harbor Freight and MidwayUSA. I have lots of them and give them
to my kids and friends. I bought a bunch of them when HF had them for $15.
I also have the MidwayUSA (Caldwell) unit--no difference.
However, they should be used over foam or some other in-the-ear plug.
Treat them as an additional form of protection and a means to overcome the attenuation of the in-the-ear plugs.
Do yourself a favor if you still have your hearing and use as much noise reduction as you can get.
None of the units rated in the NPR 20's provide enough.
I don't remember where I encountered the following but it is a good and enlightening read.
Check out:
http://www2a.cdc.gov/hp-devices/huntershooters.html
Here is the text without the tables:
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In most cases, the sound level from firing a weapon is sufficient to require the use of hearing protection, even if the weapon is fired only one time. Recent NIOSH studies of sound levels from weapons fires have shown that they may range from a low of 144 dB SPL for small caliber weapons such as a 0.22 caliber rifle to as high as a 172 dB SPL for a 0.357 caliber revolver.
Consequently, NIOSH recommends that hunters and shooters use double hearing protection each and every time a weapon is fired. Double protection involves wearing both earplugs and earmuffs. The best combination is a deeply inserted foam earplug and a well-seated earmuff.
NIOSH examined the performance of several types of hearing protectors with a variety of weapons. Earplugs were able to reduce the peak sound pressure level by 10 to 30 decibels and earmuffs yielded 20 to 38 decibels of peak reduction. Active level-dependent earmuffs were found to react sufficiently fast to provide the same protection level as when they were turned off [Murphy and Little (2002) J. Acoust. Soc. Am. 111:2336; Franks and Murphy, (2002). J. Acoust. Soc. Am. 112:2294]. The effect of volume gain setting was minimal for active level-dependent devices (see Figure 1). Each protector was tested with the volume set for unity gain, maximum gain or turned off. At unity gain the sound under the protector is as loud as when no protector is worn. The peak reduction was mostly unaffected by the change in the volume setting.
The formula for determining the maximum number of shots is:
10(140-pldB)/10
where pldB is the peak level of the sound in the ear canal under the earmuff and earplug. NIOSH recommends that peak exposures be limited to one event not exceeding a peak level of 140 dB SPL. That is, exposure to one event of 140 dB SPL would constitute 100% of a persons’s noise burden.
As shown in Figure 2, the amount of reduction for 12-gauge shotgun using the David Clark Model 27 earmuff is 31 dB, reducing the peak level from 161(red line) to 130 dB SPL( blue line). So, with the earmuff alone, the number of shots recommended by NIOSH would be five per 24-hour period. The addition of a deeply inserted foam earplug reduces another 21 dB, increasing the allowed number of shots to more than 1200 per 24-hour period. A smaller caliber weapon with a lower peak level, such as 0.22 caliber rifles with peak levels of 144 dB SPL, could be fired as many as 63000 rounds per 24-hour period if the shooter were to wear an active level-dependent earmuff along with a deeply inserted foam earplug. The combination of an earmuff and a deeply-inserted foam earplug can provide as much as 50 dB of peak reduction, which is adequate in most cases.
Double hearing protection can severely compromise the ability to communicate when both devices are passive, linear protectors. The use of an active level-dependent earmuff with a deeply-inserted foam earplug can compensate for the loss of communication ability when double protected. In some cases, the earmuff may provide sufficient gain to counter the attenuation of the earplug.
For shooters, a key indication that whatever protection is being used is inadequate is ringing of the ears or a feeling of fullness in the ears after an episode of shooting.
There are also active level-dependent hearing protectors that are built into pre-molded earplugs and custom earplugs as well on the market. There are no data on their effectiveness. At present, there are no data on the use of an active level-dependent earplug in combination with a passive earmuff. Given the attenuation chain, it is doubtful that the pairing would be as effective as the active level-dependent earmuff with foam earplug.
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Kind Regards,
Tom
Anyway, I think I'm ready for them and honestly untill last Saturday when I was having dinner with a fellow member of this forum, I did not know they even existed!! 
