Hearing Aid Blog

How Nature Protects the Eardrum

December 28, 2009

The eardrum is a highly sensitive membrane and nature has taken various precautions to protect it from damage:

Cerumen (earwax): The external part of the ear canal contains sweat and sebaceous glands. The glands produce a waxy substance known as cerumen or earwax, which traps bacteria and dust. Cerumen is only produced in the outer third of the ear canal where it can be removed. Never try to clean down inside of the canal yourself. If you have a problem, consult your hearing care professional or physician.

Protective hair: The external part of the ear canal is covered with tiny hairs that act like a curtain to protect the eardrum from dust and dirt. If dust or bacteria do succeed in penetrating the curtain they are trapped by the cerumen.

Ear canal: The eardrum is further protected by bends in the ear canal. This helps prevent objects accidentally entering the ear and damaging the eardrum.

Cerumen and hearing instruments: When you first start wearing a hearing instrument, it often seems like a foreign object in the ear. This feeling disappears after a short familiarization period. All the same, hearing instruments can stimulate the production of cerumen. Some instruments are equipped with a protective cerumen filter to help prevent earwax from entering the instrument. If the outlet of the hearing instrument is blocked by earwax, the volume may be reduced or even cut-off altogether.

How much noise can your ears take?

September 30, 2009

This is a question that OSHA (occupational safety and health administration)  has had to come up with answer to in order to protect workers’ hearing in loud environments (like many factories) from dangerously high noise exposure.

Below is the chart they came up with (this chart assumes the worker is wearing ear plugs and ear muffs):

TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________
                            |
  Duration per day, hours   | Sound level dBA slow response
____________________________|_________________________________
                            |
8...........................|                    90
6...........................|                    92
4...........................|                    95
3...........................|                    97
2...........................|                   100
1 1/2 ......................|                   102
1...........................|                   105
1/2 ........................|                   110
1/4  or less................|                   115
____________________________|_______________________________

So, for example, if you work in an environment that is 111dB, you should not be in that environment for more than 1/2 an hour, even with earplugs and muffs on.  Cumulative effects should also be considered.  So if you are in that same environment multiple times per day, there’s a formula that you need to use to figure out what’s legally allowed.  If anyone is interested in the formula you can post a comment, or go to the OSHA website.

Some people are more susceptible to noise damage than others, and certain types of noise (regardless of decibel level) are more likely to hurt your hearing.  Without getting into a lot of detail, some people are less prone to noise damage because of an anti-oxidant effect in their inner ear; some people naturally have more anti-oxidants.  Women, for example have more protection because estrogen is an anti-oxidant, and darker skinned people have more anti-oxidants because they have more melanin.  A natural deduction is that if you load up on a water-soluable anti-oxidant like vitamin C, you’ll have more protection, and studies suggest that that is, in fact, likely.  Although, there are problems with overdosing on vitamin C, so you have to be careful.

With regard to decibel level and damage, studies show something unusual…that if steady-state noise is present before (and during) a loud impact noise, your ears are less likely to be damaged than if that same impact noise was made without having a steady state background noise present beforehand.  Hearing scientist, Don Henderson, coined the phenomenon, the “toughening effect.”

Bottom line here is that you shouldn’t be in noisy situations for too long or it will damage your hearing, and even though there are some things you can do to help prevent it – most obviously – wearing  hearing protection – noise still should be avoided.    When you do where earplugs, it’s good to also wear muffs on top of the plugs to get extra attenuation.