Monthly Archives: June 2013

Mixed hearing loss – a combination of conductive and sensori-neural 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. 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.

Previous posts have focused on two different types of hearing loss: conductive and sensori-neural. Today’s post will focus post on mixed hearing loss which occurs when a person has a sensori-neural hearing loss but may experience some conductive hearing loss as well.

Generally speaking, sounds are “conducted” from the environment around us down our ear canals (outer ear), causing the ear drums to vibrate. The movement of the ear drums causes 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. 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.

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.

Sensori-neural hearing loss, typically referred to as “nerve deafness”, occurs when damage most often occurs in the “inner” ear but can also occur along the hearing nerve.

Approximately 90% of people who have hearing impairment have sensori-neural hearing loss, making it the most common type of hearing impairment. Generally speaking, sensori-neural hearing loss is permanent and irreversible.

In the vast majority of cases, sensori-neural hearing loss is not medically or surgically treatable. However, most people with sensori-neural loss notice a great deal of benefit from wearing some form of amplification devices (hearing aids, bone-anchored hearing aid (BAHA), cochlear implants, etc.).

A mixed hearing loss occurs when a person experiences a combination of conductive and sensori-neural hearing loss. There may be problems in the outer and/or middle ear as well as the inner ear. One example of a mixed hearing loss is a conductive loss due to a middle-ear infection or wax build up combined with a sensori-neural loss associated with aging.

I have seen several patients over the years who have developed a sensori-neural hearing loss and who wear hearing aids. Occasionally, these individuals develop an ear infection or wax build-up in their ear canals. These conditions may cause more hearing loss. Most often these people will complain that their hearing aids are not loud enough or think that there is something wrong with their hearing aids.

In such instances, I would examine the ear canals and ear drums and perform a battery of tests to check for any changes. Typically my tests would indicate that there is a conductive component to their hearing loss.

I would recommend them to their family physician with a copy of my most recent results.The doctor would review my results and check the patient’s ears for any sign of ear infection or wax. Some of the clients may be referred to an ear, nose and throat doctor.

Typically, the hearing loss associated with these conditions is temporary and would return to where it was before the conductive portion of the hearing loss. Once the conductive portion of the hearing loss is gone, the hearing aids would perform the way they did before the condition. The person would still have the sensori-neural portion of the hearing loss but the conductive hearing loss would be gone.

Treating any hearing loss depends on prompt diagnosis and treatment. Whenever a person experiences some form of hearing loss, they should be evaluated as soon as possible by an audiologist and physician to explore all potential treatment options.

Glen Sutherland, MCISc

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.

A forced rest and two lessons

I have not posted anything on my blog for a month and there is a good reason for that. I have been ill and had to take some pretty heavy duty pain killers for about three weeks or so. Taking these pills resulted in two things. First, I slept – a lot! And when you sleep, you don’t wear any of the external parts of your implant so I wasn’t getting the usual sound stimulation. And secondly my brain pretty much turned to mush so I also wasn’t thinking very well. In fact a couple of weeks ago I composed a very brief email to one of my clients and had to re-write it three times so it would make sense! A posting was not in the cards.

I’m fine now but have noticed that being without my external processor for so long has resulted in my going backwards a bit. I’m not hearing as well as I was before. Some of this is due to the normal fatigue that comes with illness, but the main reason I think is that my brain is out of practice.

So a couple of lessons for me. One, my audiologist is right – I do need to wear the external processor from the moment I get up to the moment I go to sleep. I generally do this but there are times when I really want to cut out the noises of life. Even though it is sometimes a relief to be in a totally silent world, it is not a good idea.

Another lesson for me – and this is a bigger one I think – is that the progress I have made in my ability to hear and understand sound over the past eight months is perceptible, even when I haven’t thought it was. The fact that I noticed a reduction in my progress from not wearing the processor for a few weeks actually tells me that I am aware of what I have accomplished. I do hope this makes sense! This is an important lesson for me at this stage of my development with the implant because the progress I make now is tiny and not always truly noticeable. So even when I feel I am not moving ahead, I actually am. My brain is getting better all the time at interpreting sound.

To add proof to this particular pudding, this morning in church, urged on by one of my friends, I decided to ‘test’ my ability to hear complex music with just the implant. To backtrack a bit, last December I tried this test for the first time. At that stage in my development, I was able to distinguish individual notes but not the complex sounds of a choral piece. While the choir was singing the anthem last December, I took out my hearing aid (which does allow me to hear some music) and just listened with my cochlear implant. There was no musical sound at all. All I heard was the choir speaking words. It actually reminded me of a Greek chorus because there was a cadence to the words. But no music. This morning when I tried the test again, I heard a little of the music the choir was singing. Tiny steps.