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Loud and clear

Choosing the right hearing protection is vital

The fundamentals of hearing protection are founded on very sturdy principles.

We know that employees must not be exposed to more than 85dB over an eight-hour
period (or equivalent), or be exposed to more than 140dB for any length of time – regardless of what hearing protection they are wearing.

So then is hearing protection just a case of simple maths?

For example, if an employee works in an area with average noise levels of 100 dB, and
they are provided with earplugs that carry an attenuation (noise reduction) value of 26 dB, how much noise is reaching the eardrums of your worker? 74dB, right? Or is it?

It is such a simple question, but so vital to a Hearing Conservation Program.

The truth is that the amount of noise reaching the eardrums of that worker is completely unknown.

Several key factors affect the amount of protection offered by hearing protectors – fit and wear-time.

Let’s focus first on fit. This is where earmuffs hold the advantage over earplugs.

It’s pretty hard to get the fitting of an earmuff wrong. Earplugs are a different matter.

Although a well fitted earplug will often provide more attenuation than is possible from
an earmuff, if it is not fitted well, it can offer very little, or no protection at all.

This has been a frustration for many years, as the AS/NZS1269 Hearing Standard has
required employers to ensure that hearing protection is being fitted and worn properly.

When it comes to earplugs, we have had no way of testing whether the individual is fitting them correctly, and secondly that they are the correct size and type for that particular worker.

Fortunately, Howard Leight’s VeriPRO technology has now provided us with the ability to fit-test earplugs.

Let us now focus on wear-time. This is where earplugs hold the advantage over earmuffs. Earmuffs are easy to fit, but too easy to remove.

How many times do we see a worker lift up an earmuff cup and say “what did you say?”
Removing hearing protection for very small amounts of time quickly voids large amounts of adequate protection. For example, a 30dB earmuff worn for 7 hours and 55 minutes of an 8 hour shift, (ie. removed for just 5 minutes of the day), provides the equivalent of 19dB of protection, not 30dB.

Because of the way that decibels work, this is only about 7 per cent of the intended protection.

So once we know that a worker is using a correctly fitted hearing protector, we also need
to know that they are wearing them at all appropriate times.

The AS/NZS1269 Hearing Standard calls this “ensure correct usage.”

Again, this is information that employers have thirsted for, and now technology can
provide the answers. QuietDose by Howard Leight conducts dosimetry with a microphone
located on the inside of the earplug or earmuff.

This allows us to see if what the worker is doing with their hearing protection. Are they
compromising it enough to cause over-exposure to hazardous amounts of noise?

For humans to operate in noise such as that produced by industry, care and precaution
must be taken, as our ears were not designed to operate in this environment.

This means that we also face considerable challenges communicating, as the human voice is drowned in such noisy environments.

If we must communicate, we need to consider solutions like transmitting voice across a short wave radio so that it arrives to the recipient without the need for them to remove any hearing protection that they are wearing.

This system must therefore have the ability to send and receive clear speech communication, whilst offering hearing protection against the noisy environment to which the worker is exposed.

Technology again has stepped up to provide quality equipment that does just this with
Howard Leight’s QPi.

When it comes to hearing, and more importantly its protection, there are now as many answers as there are questions.

We just have to know where to look.

Sperian Protection Australia Pty Ltd
Ph: 03 9565 3509
www.sperianprotection.com.au