Quick question: if you could have one thousand dollars today or two thousand in a year, which would you choose?
If you’re like most people, you would take the cash now, even though it's only half as much. That's because of a cognitive bias known as "hyperbolic discounting." It's the way our psychology works - we perceive things in the future as having a lesser effect than those that are immediate.
That same bias leads us to tolerate risks we would never consider if the consequences were immediate. Our brains tend to think that tings in the future just matter less.
(Learn more in Safety and Overconfidence.)
If a supervisor was giving instructions to a worker and added at the end, “Oh, by the way, after you do this you will be partially deafened for life,” there wouldn’t be many takers for the task. Yet, as long as the consequence is at some ill-defined, foggy time in the future, workers happily comply. In fact, some workers even fail to protect hearing in direct defiance of instructions – tearing one earplug in half so that they appear to be wearing them, taking them out when supervisors aren't around, or deliberately having them inserted half way.
How Noisy is Too Noisy?
Employees may not feel like the noise they're exposed to is damaging to their hearing. But if they've been assigned a set of earplugs or earmuffs by their supervisor, chances are the exposure levels are hazardous.
But what exactly counts as hazardous noise?
The commonly accepted level of sound energy that we can theoretically be exposed to for 8 hours a day without incurring damage is 85 decibels. At or above that limit of exposure day after day, some hearing damage is very likely to occur.
When assessing a site, it's important to remember that decibels are measured on a logarithmic scale, so that every 10 decibels represents double the energy. 110dB isn't 10 percent louder than 100dB – it's twice as loud!
The level of noise at a work site has some implications for the selection of hearing protection. Whether plugs, muffs, or double protection are needed may vary from one part of a site to the next.
(Find out How to Reduce Noise Levels in Your Workplace.)
The Mechanism of Hearing Loss
To understand hearing loss, we have to understand how excessive noise affects the auditory system.
Vibrations in the air enter our ears through the auricle (exterior ear) and travel down the auditory canal to the tympanic membrane (ear drum). That membrane translates the vibration to three tiny bones called the ossicles: the malleus (hammer), incus (anvil), and stapes (stirrup). The vibrating stapes is connected to another membrane called the oval window, which conveys the vibrations into the liquid medium in the coiled canal of the cochlea. As the pressure wave travels down the coiled tube, it moves specialized hair cells on the organ of Corti, which converts mechanical energy into a nerve potential. Ultimately, the brain receives the signal, and we hear a sound.
Don't worry - the glossary of Latin terms will not be on the final exam.
The last steps in the hearing process are important to our discussion because that's where noise-induced hearing loss occurs.
The hair cells that detect movement in the cochlea are arranged such that the outermost ones are tuned to detect higher frequency vibration (high-pitch sound), and are most sensitive to damage from excessive noise. The hairs will gradually break off or otherwise degrade, and sounds in that range will become less and less audible.
High pitches are lost first, and to some degree this happens naturally as we age, but it's exacerbated and accelerated by noise exposure. These sensitive hairs are a single point of failure for the system, and once damaged they never grow back.
Hearing loss is gradual, aggregate and irreversible. Upper management needs to have an understanding of this because protecting workers from work-related hearing loss is considered their responsibility.
What should diligent management do about hearing protection, exactly?
They should facilitate the creation of a hearing conservation program, covering key requirements:
- A noise survey of the work sites they control
- Information on how to select appropriate protection
- Audiometric testing
- Training and inspections
Senior management should lead in the implementation and review of the program, taking care to ensure it is being communicated to all workers, and that it is effective.
Noise-induced hearing loss is preventable in most cases. The mechanism of damage has long been known and prevention relatively easy, so worker's compensation authorities hold employers responsible if they fail to protect workers – even long after the fact.
It's not enough to have a box of earplugs somewhere in the tool crib or in an office cabinet. Management has to be diligent in making sure workers are complying with hearing protection guidelines. This means that supervisors have to be trained on their responsibilities to ensure hearing protection is used, and used properly. Inspections should ensure that all required PPE is in use, including required hearing protection.
(Find out Who Pays for Personal Protective Equipment?)
Workers have to be educated on noise as a hazard and what to do about it, and most importantly, the risks of failing to protect their hearing.
You Get Used to It
Have you ever turned on your car and get suddenly blasted with unbearably loud music? The volume setting didn't seem uncomfortable the last time you were driving, but now it seems way too loud.
That happens because we acclimate to high volume the longer we stay in loud environments, This is exactly why we can't rely on individuals to determine for themselves whether their surroundings are loud, or to use perceived noisiness as a prompt to don hearing protection.
Usually, the baseline volume is high all around you, so the auditory system undergoes a “temporary threshold shift” and you won't typically notice how loud your environment is until after you've been in it for a period of time.
For that reason, management has to be diligent in ensuring that everyone on their sites protect their hearing. Workers get used to loud, harsh noises. It's your job to make sure they remember that it is damaging their hearing, even if it doesn't feel that way.
|Free Download: Causes, Consequences, and Costs of Occupational Hearing Loss |
What Do You Have to Lose?
Psychologists say that vision loss disconnects you from the world in some ways, but being unable to hear disconnects you from people. Real hearing loss is a terrible impairment, one for which there is no cure. The only remedy is to amplify sound with a hearing aid so that it can be heard again, but depending on the degree of damage this may only work so well, and for so long.
A glance around some work sites today is a chance to see the hearing loss claims of tomorrow as they develop, which is a great shame. Management is responsible for providing a safe working environment for all workers, and that means the onus is on management to protect hearing. Sounds like a worthwhile priority to me.