Electronic ear muffs

[Oldbloke]

NRR Method (USA)
When hearing protection is worn, your level of exposure is based on the NRR rating of the protection device being used. Keep in mind however that while the NRR is measured in decibels, the hearing protector being used does not reduce the noise exposure to the ear by the same number of decibels associated with the protector. For example if you are at a rock concert and the noise you are exposed to is 100 dB and you put on a pair of NRR 27 muffs the exposure will not be reduced to 73 dB, as you may expect. Rather the reduction is calculated like this, (27-7/2 = 10 dB)

Therefore you are exposed to 100dB and wear a pair of NRR 27 rated muffs 100-10 = 90.0 dB exposure to the ear.
These are Class 1 muffs under the Australian system (the lowest/poorest)

The SLC80 method (Australia)
The workplace noise is measured in C-weighted sound pressure levels as average over the shift, [LCeq,8h]. The SLC80 (Sound Level Conversion valid for 80% of the wearers) of the hearing protector indicates the difference between the measured C-weighted sound pressure level of the workplace noise outside the hearing protector and the A-weighted sound pressure level, attenuated by the hearing protector, under the hearing protector inside the ear canals.
For example the noise level in a workplace was 100 dB(C) (as average over the shift). If you are exposed to a noise level of 100 dB and then wear a Class 5 muff with a rating of 30 dB
100 – 30 = 70 dB(A) exposure to the ear

Australian class system
Class 1. 10 - 13
Class 2. 14 - 17
Class 3. 18 – 21
Class 4. 22 - 25
Class 5. 26 or greater

I hope this further explains the system. Beware of NRR muffs!

[jastreb]

Yes I realise what you are saying. The top link I sent though is the Australian website for honeywell. It lists the ratings for the Impact Pro's for all the major standards.

American NRR 30
European SNR 33
Australia and NZ SLC80 31

The that would make them a Class 5 SLC80 31dB Ear Muffs.

Below are the regulations and codes they adhere to.

1 The EPA labeling standard is defined in Code of Federal Regulations (CFR) 40, Part 211, Subpart B – Hearing Protective Devices.

2 The SNR rating and HML descriptors are defined in ISO 4869-2, Acoustics – Hearing Protectors.
3 The SLC80 is defined in Australian/New Zealand Standard 1270:2002, Acoustics – Hearing Protectors.

For further info on Howard Leight's attempt to explain ratings visit the link below which will download a pdf file.

http://www.howardleight.com/images/pdf/ ... atings.pdf

[kritch]

You're really up on this stuff huh old bloke.

You work in making these things or something?

[Oldbloke]

Kritch,

I guess I am up with it. I work as an OHS/WHS Professional/Generalist. (when I'm working, looking at the moment) Noise & the reduction of noise exposure is just one small area of many that I am interested & work in.

As a shooter/hunter I am very aware of the noise hazard to fellow shooters. Young blokes in particular often tough it out thinking it "wont happen to them" & are therefore at higher risk of hearing loss later in life.

I am also aware that few people understand the hazard well, so when I get the opportunity I like to educate them. The info I provide should help them ( and everyone else) to make good choices and perhaps help them to better enjoy the music, esp later in life.

I am also just one of the boys & like a beer.

[kritch]

I am also just one of the boys & like a beer.

ha ha.

Not an easy task lecturing everyone on hearing safety at the range I'm sure

I'd be taking the beer option instead as well

[Squiddy]

Are ozito still available at Bunnings?

[Oldbloke]

Dont know but they wear out fairly quickly as the quality is not there.