Conductive Hearing Loss

Did you know that there are different types of hearing loss? Depending on where you are experiencing problems in your ear will determine what type of hearing loss you have and what help you can get to improve your particular situation.

Today’s post will focus on conductive hearing losses and the next post will focus on sensori-neural hearing losses. When you get your hearing tested, you undergo a series of tests which help the clinician ascertain which type of hearing loss you have. The results of the tests also help the clinician recommend how you can best be helped depending on your type of hearing loss.

If you have not already done so, you might find it helpful to read my previous posts.

If you think a picture of the auditory or hearing system would be helpful while you read this post, simply, type, “anatomy/images of the ear” into your favourite browser and you will see many links to pictures of the ear.

The ear per se is divided into three sections: the outer ear, the middle ear and the inner ear. The outer ear consists of the parts of the ear that you can examine visually, including the ear canal and the ear drum.

Just beyond the ear drum is the middle ear which contains the three smallest bones in the human body, the malleus (hammer), incus (anvil) and stapes (stirrup). These bones connect the outer ear to the inner ear.

The inner ear (cochlea) is a snail-shell shaped cavity in the temporal bone of the skull. It is filled with a special fluid and hundreds of thousands of tiny hair cells.

So, how do we hear? Generally speaking, sounds are “conducted” from the environment around us down our ear canals, causing the ear drums to vibrate. The movement of the ear drums cause the bones in the middle ear to vibrate against the oval windows which sit at the entrance of the inner ear. The inner ear hair cells change the vibrations from the middle ear into electrical impulses which are sent along the auditory nerve to the brain which makes sense of the things we hear around us.

Because the outer and middle ears are responsible for “conducting” sounds to the inner ears, anything that can go wrong with the outer and/or middle ears result in “conductive” hearing loss.

Conductive hearing loss may result from a variety of reasons which include but are not limited to, earwax blocking the ear canal, fluid in the middle ear, middle ear infection, obstructions in the ear canal, deformations, perforations (hole) in the eardrum, hardening or breaking of the bones in the middle ear and pressure build up due to issues with the Eustachian Tube.

A conductive hearing loss results in a reduction of loudness of sound reaching the inner ear. Some people say it is like listening under water. They feel like their ears are plugged. As well, people with conductive hearing loss tend to speak softer than usual because they hear their own voice loudly.

Try this little experiment:
1. Put your forefingers (index fingers) over the portions of the ears that sit over the entrance of your ear canals (tragi).
2. Press on the tragi so they block the entrance to both ear canals.
3. Have someone speak to you. You should be able to hear them but at a softer level than normal.
4. Talk to yourself. You should sound louder and your voice should sound like it is “inside” your own voice.
5. Try eating a carrot or some celery. The crunch of the vegetables should sound much louder to you.

Generally speaking, because the problems associated with conductive hearing loss are in the outer and/or middle ear, the inner ear hair cells are still working well and can transmit any sounds that are picked up to the brain. Simply put, when a person experiences a conductive hearing loss, sounds will be softer but won’t be distorted.

Imagine the following sentence to be what it would be like to hearing through an intact or healthy auditory system:

THE QUICK BROWN FOX JUMPED OVER THE LAZY DOGS.

When a person experiences a conductive hearing loss, the same sentence would look something like the following sentence:

ThE quick BROWN FOX jUMPED OVER THE LAzY DOGs.

Notice that some of the letters appear smaller in the second sentence. This sentence attempts to illustrate that sounds are getting through to the inner ear but not with as much power because something isn’t as it should be along the “conductive” portion of the ear (the outer/middle ear). The transmission of sound is impeded and results in a conductive hearing loss.

Most conductive hearing losses are temporary and are resolved following medical treatment such as medication and/or an operation. Conductive hearing losses can also be permanent and may require hearing aids or implantable bone-anchored hearing implants.

Treating any hearing loss depends on prompt diagnosis and treatment. All conductive hearing losses should be evaluated by an audiologist and physician to explore all potential treatment options.

Glen Sutherland, MCISc
Audiologist

Disclaimer
Please note that the information in this blog is presented for the purpose of providing information and should not be used for medical diagnosis or treatment nor should it be used in place of medical advice from your doctor or hearing health care professional.

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