How We Hear... Part 1

Have you ever stopped to think about how incredible your ears are?  The fact that we can hear at all and with such amazing clarity is really a miracle of design and function.  Let's talk a little about how our marvelous ears work.

To hear sound, your ear has to do three basic things:

•Direct the sound waves into the hearing part of the ear

•Sense the fluctuations in air pressure

•Translate these fluctuations into an electrical signal that your brain can understand

The pinna, the outer part of the ear, serves to "catch" the sound waves. Your outer ear is pointed forward and it has a number of curves. This structure helps you determine the direction of a sound. If a sound is coming from behind you or above you, it will bounce off the pinna in a different way than if it is coming from in front of you or below you. This sound reflection alters the pattern of the sound wave. Your brain recognizes distinctive patterns and determines whether the sound is in front of you, behind you, above you or below you.

Your brain determines the horizontal position of a sound by comparing the information coming from your two ears. If the sound is to your left, it will arrive at your left ear a little bit sooner than it arrives at your right ear. It will also be a little bit louder in your left ear than your right ear.

Once the sound waves travel into the ear canal, they vibrate the tympanic membrane, commonly called the eardrum. The eardrum is a thin, cone-shaped piece of skin, about 10 millimeters (0.4 inches) wide. It is positioned between the ear canal and the middle ear. The middle ear is connected to the throat via the eustachian tube. Since air from the atmosphere flows in from your outer ear as well as your mouth, the air pressure on both sides of the eardrum remains equal. This pressure balance lets your eardrum move freely back and forth


The eardrum is rigid, and very sensitive. Even the slightest air-pressure fluctuations will move it back and forth. It is attached to the tensor tympani muscle, which constantly pulls it inward. This keeps the entire membrane taut so it will vibrate no matter which part of it is hit by a sound wave.

The compressions and rarefactions in sound waves move your eardrum back and forth. For the most part, these changes in air pressure are extremely small. They don't apply much force on the eardrum, but the eardrum is so sensitive that this minimal force moves it a good distance.


The cochlea in the inner ear conducts sound through a fluid, instead of through air. This fluid has a much higher inertia than air -- that is, it is harder to move (think of pushing air versus pushing water). The small force felt at the eardrum is not strong enough to move this fluid. Before the sound passes on to the inner ear, the total pressure (force per unit of area) must be amplified.

This is the job of the ossicles, a group of tiny bones in the middle ear. The ossicles are actually the smallest bones in your body. They include:
•The malleus, commonly called the hammer
•The incus, commonly called the anvil

•The stapes, commonly called the stirrup

When air-pressure compression pushes in on the eardrum, the ossicles move so that the faceplate of the stapes pushes in on the cochlear fluid. When air-pressure rarefaction pulls out on the eardrum, the ossicles move so that the faceplate of the stapes pulls in on the fluid. Essentially, the stapes acts as a piston, creating waves in the inner-ear fluid to represent the air-pressure fluctuations of the sound wave.


This amplification system is extremely effective. The pressure applied to the cochlear fluid is about 22 times the pressure felt at the eardrum. This pressure amplification is enough to pass the sound information on to the inner ear, where it is translated into nerve impulses the brain can understand.

The cochlea is by far the most complex part of the ear. Its job is to take the physical vibrations caused by the sound wave and translate them into electrical information the brain can recognize as distinct sound.

Next time, we'll learn about how the cochlea translates that physical energy into electrical information...

This Year I Will...

During the last three days back at work, I think that I have written 2010 instead of 2011 nine out of ten times.  I can't believe that we are in a new year already!

January is the month of resolutions.  Things we all do for a week or two, and then find ourselve back in our old ways.  (I wonder just how many people are on diets right now that weren't on them a month ago?)  Why is it that we all make goals that we realistically won't keep?

One simple resolution that can make a huge difference for many people-- not only personally, but to their families as well is the goal to hear better.  Studies have shown that it takes an average of 7 years from the time a person first notices a hearing loss until the time where they actually do something about it.  During those 7 years, gradual changes take place where the person finds themselves less in touch with their family and friends, not as engaged in their work or social lives, and generally socially isolated.

Don't let 7 years worth of damage done by hearing loss affect your life.  We always tell our patients this-- we promise that your hearing loss is much more noticeable then the nearly invisible hearing technology that we have available now. 

"Resolve" to hear better today!!

New Study Indicates New Reason For Age-Related Hearing Loss

Millions of tiny sensory heir cells in the inner ear enable you to hear. Age-related hearing loss involves the death of some of these sensory hair, nerve and membrane cells. Since the hair and nerve cells do not regenerate in humans, their death leads to permanent hearing loss.

Researchers in the USA have now, with the help of research on mice, found out that these sensory hair cells can be destroyed if the so-called mitochondrial membrane, which protects the cells, is destroyed. This can occur if there is too much Bak protein present. Should this happen, proteins can find their way into the cells and break them down, causing the cells to die. Bak is typically induced by oxidative stress and its levels increase as people age.

So if oxidative stress triggers damage and death of hearing-related cells, enhancing the antioxidant defences of the mitochondria should reduce such damage, says postdoctoral researcher Jinze Xu, one of the researchers behind the study.

The studies with the mice show, that older mice without Bak protein have the same good hearing as young mice.

It is estimated that in the USA alone more than 28 million Americans will be affected by the condition by 2030.

Source: www.eurekalert.org, www.pnas.org

Hearing Loss More Likely In Individuals With Chronic Kidney Disease

Individuals with moderate chronic kidney disease (CKD) are more likely to suffer from hearing difficulties compared to healthy people of the same age, researchers have revealed in an article that appears in the American Journal of Kidney Disease.

Researchers from the Universities of Sydney, Melbourne and Macquarie in Australia examined the medical records of 2,564 people aged 50 or more, of whom 513 had moderate CKD.

More that 55 % of all the patients with CKD had some degree of hearing loss. Among people who had no kidney problems less than 30 % had hearing loss. Furthermore, severe hearing loss affected almost 30% of the CKD patients, compared to just 10% of the others.

The figures were adjusted for other risk factors that may affect hearing, such as age, sex, noise exposure, diabetes and more.

Possible explanations

University of Sydney, said:

The link between hearing loss and CKD can be explained by structural and functional similarities between tissues in the inner ear and in the kidney. Additionally, toxins that accumulate in kidney failure can damage nerves, including those in the inner ear. Another reason for this connection is that kidney disease and hearing loss share common risk factors, including diabetes, high blood pressure and advanced age.

What is chronic kidney disease?

Chronic kidney disease is a slow and progressive loss of kidney function. Over a period of several years the condition worsens until eventually there is permanent kidney failure. Many people don't know they have CKD until their kidney function is down to 25% of normal. The main causes of CKD are diabetes and hypertension (high blood pressure).

Source: www.medicalnewstoday.com

Free Hearing Aids For Christmas

Christmas is a time for family. It is a time for music and laughter and enjoying memories with friends and loved ones.


None of these things is possible with a hearing loss.

Timpanogos Hearing and Balance in American Fork is happy to announce that they will be giving away a set of digital hearing devices to one recipient for Christmas—no strings attached.

“We’ve been able to help thousands of people to hear better over the last 7 years, but we realize that there are many more out there who need to hear better, but can’t afford it. I became an Audiologist to help people to hear better—as many people as I can. We are grateful to be in a position where we can give back to the community and help someone who has no other way to help themselves,” says Dr. Layne Garrett, owner of Timpanogos Hearing and Balance.

The hearing devices will be given away based on need and on their ability to truly make a difference in the recipient’s life. You may nominate yourself or someone else. To apply, write a 500 word description of how hearing better could make a difference for the applicant. Attach the person’s name, age, city of residence, and phone number. You can email this information to Christmas@utahhearingaids.com, fax it to 801-763-8282, or mail it to Timpanogos Hearing and Balance 321 E 300 N American Fork, UT 84003.  You can also click here to fill out an online form.

Applications must be received by December 12th.

Men Are More Likely to Experience Noise Induced Hearing Loss

For years, we've known that about 60% of our patients are men.  We've come up with a few theories for this, but recently, we discovered a study that confirms one of them:  men are more likely to experience noise-induced hearing loss.

In the first study of the demographics of noise-induced hearing loss (NIHL), researchers found men are 2.5 times more likely to lose their hearing due to noise than women. Over 5,000 participants between 20 and 69 years of age were analyzed with audiometric testing. More than 13 percent suffered from NIHL. Especially white married men are significantly more at risk than women concludes the report which was presented at the 2009 American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) Annual Meeting & OTO EXPO


NIHL is a preventable and increasingly prevalent disorder that results from exposure to high-intensity sound, especially over a long period of time. Researchers hope this study will put more focus on education and prevention and lead to increased screenings for the common problem.

The authors believe this is the first study of its kind to delve in to the demographics of NIHL using the most recent figures from 1999-2004 National Health and Nutrition Examination Surveys (NHANES). They believe this information can allow greater education, preventative, and screening efforts.

Source: Ivanhoe Broadcast News and redOrbit

Seriously First Class Hearing

Every few years, something happens in the hearing technology industry which pushes everything forward by leaps and bounds.  Open fit hearing aids did that a few years ago.  Phonak has just released a new product with some features that promise to push that envelope again.  They call it the Ambra.

The Ambra is a true First Class communication device.  We refuse to call it a hearing aid for the simple reason that, if it works as promised, the Ambra will enable a person with a hearing loss to actually hear in certain situations as well as (and just maybe even better) than a normal hearing person.

You read right.  Better.

Here's how they do it.

This is an illustration of standard, monaural directional microphones.  Monaural directional microphones have a broad forward focus (gray beam) enabling improved audibility for all sounds within the beam.  However, they have always had a problem with one-one-one communication in a noisy environment.

 StereoZoom enables the wearer to narrow the beam further and focus on a single speaker, while suppressing other interfering sounds. Communication, even in situations which were considered impossible, is now possible.

The introduction of ZoomControl revolutionized directional hearing and set a benchmark for binaural
processing.  It automatically tracks and focuses on speech, regardless of the direction, without the need to face the speaker. Once activated, auto ZoomControl automatically selects the direction of the dominant speech source.  For example, when driving in a car, the hearing device will focus on whomever is talking-- regardless if they are in the front seat or in the back.

When focusing to one side, the speech signal is picked up and amplified by the instrument on that side; simultaneously the entire signal is streamed to the other ear. As a result, the desired signal is heard in both ears, dramatically improving the signal-to-noise ratio (SNR). This unique feature provides natural binaural listening with all of its advantages.

It is this feature that will allow those wearing the devices (even if they have a hearing loss) to have a significant communication advantage in noisy places over those without the device (even those with perfectly normal hearing.)  You may soon find people with normal hearing wearing these devices in restaurants, at trade shows, and in other noisy environments.

We are just fitting our first of these devices this week, but so far the results are encouraging.  We will definitely keep an eye on this technology and let you know if it really is as good as it says that it is!