How You Hear
Hearing begins when the outer ear, the visible portion of the ear that is on the outside of the head, channels sound waves down the auditory canal. This tube-like passageway is lined with tiny hairs and small glands that produce ear wax.
The middle ear lies at the end of the auditory canal. It is composed of the eardrum and three small bones, known by the layman as the hammer, the anvil and the stirrup. When sound waves hit the eardrum, it vibrates and, in turn, moves the hammer. The hammer moves the anvil, which moves the stirrup, transmitting the vibrations into the inner ear. The middle ear functions to amplify sound, which is why significant hearing loss can result from any disruption in any of the parts.
The inner ear consists of the cochlea and the nerve of hearing. It converts sound waves into nerve impulses that travel to the brain via the movement of tiny hair cells. The brain, in turn, allows us to hear…as long as the message it is receiving is not distorted due to problems in the process just described.
Many people suffer from hearing loss…
In fact, the latest available statistics show that approximately 20% of the United States population reports difficulty, not only HEARING what people are saying, but also UNDERSTANDING what people are saying.
That’s why my Patient’s tell me all the time: “I can hear when people are talking, but I just can’t understand what they are saying”.
I can explain why when you visit our office.
Why not call now for an appointment? +1 (850) 678-3277
Causes of Hearing Loss
One of the most common “myths” about hearing loss is that only “old people” suffer from it! In fact, the reverse is true! The majority (65%) of people with hearing loss are younger than 65 and six million people in the U.S. between 18 and 44 suffer from hearing loss (Better Hearing Institute website).
The truth is that there are several causes of hearing loss with “exposure to noise” ranking high among the reasons. The primary causes of hearing loss are:
- Exposure to noise
- Family history of hearing loss
- Aging process
- Head trauma
Types of Hearing Loss
Not all hearing loss can be corrected through the use of hearing aids or alternative listening devices. The type of hearing loss determines the specific treatment required.
There are four types of hearing loss:
- Conductive: This could be caused by something as simple as earwax buildup!
- Sensorineural: This is caused when tiny hairs in the cochlea are missing or damaged.
- Mixed: This is a combination of conductive and sensorineural hearing loss.
- Central: Strokes and central nerve diseases are often the cause of this type of hearing loss.
Hearing Loss Linked to Accelerated Brain Tissue Loss
Although the brain becomes smaller with age, the shrinkage seems to be fast-tracked in older adults with hearing loss, according to the results of a study by researchers from Johns Hopkins and the National Institute on Aging. The findings add to a growing list of health consequences associated with hearing loss, including increased risk of dementia, falls, hospitalizations, and diminished physical and mental health overall. For the study, Frank Lin, M.D., Ph.D., and his colleagues used information from the ongoing Baltimore Longitudinal Study of Aging to compare brain changes over time between adults with normal hearing and adults with impaired hearing. The Baltimore Longitudinal Study of Aging was started in 1958 by the National Institute on Aging to track various health factors in thousands of men and women.
Previous research from other studies had linked hearing loss with marked differences in brain structure compared to those with normal hearing, both in humans and animals. In particular, structures that process information from sound tended to be smaller in size in people and animals with impaired hearing. Lin, an assistant professor at the Johns Hopkins University schools of medicine and public health, says it was unknown, however, whether these brain structural differences occurred before or after hearing loss.
As part of the Baltimore Longitudinal Study of Aging, 126 participants underwent yearly magnetic resonance imaging (MRI) to track brain changes for up to 10 years.
Each also had complete physicals at the time of the first MRI in 1994, including hearing tests. At the starting point, 75 had normal hearing, and 51 had impaired hearing, with at least a 25-decibel loss.
After analyzing their MRIs over the following years, Lin and his colleagues, reporting in an upcoming issue of Neuro image, say those participants whose hearing was already impaired at the start of the sub-study had accelerated rates of brain atrophy compared to those with normal hearing. Overall, the scientists report, those with impaired hearing lost more than an additional cubic centimeter of brain tissue each year compared with those with normal hearing. Those with impaired hearing also had significantly more shrinkage in particular regions, including the superior, middle and inferior temporal gyri, brain structures responsible for processing sound and speech.
That structures responsible for sound and speech are affected in those with hearing loss wasn’t a surprise, says Lin — shrinkage in those areas might simply be a consequence of an “impoverished” auditory cortex, which could become atrophied from lack of stimulation. However, he adds, these structures don’t work in isolation, and their responsibilities don’t end at sorting out sounds and language. The middle and inferior temporal gyri, for example, also play roles in memory and sensory integration and have been shown to be involved in the early stages of mild cognitive impairment and Alzheimer’s disease. “Our results suggest that hearing loss could be another ‘hit’ on the brain in many ways,” Lin explains.
The study also gives some urgency to treating hearing loss rather than ignoring it. “If you want to address hearing loss well,” Lin says, “you want to do it sooner rather than later. If hearing loss is potentially contributing to these differences we’re seeing on MRI, you want to treat it before these brain structural changes take place.” Lin and his colleagues say they plan to eventually examine whether treating hearing loss early can reduce the risk of associated health problems. The research was supported by the intramural research program of the National Institute on Aging, the National Institutes of Health’s National Institute on Deafness and other Communication Disorders (K23DC011279), a Triological Society/American College of Surgeons Clinical Scientist Development Award and the Eleanor Schwartz Charitable Foundation.
ADULT HEARING HEALTH QUIZ
If you or a loved one are wondering about their hearing, there is probably a good reason. A decrease in hearing ability affects people differently, and the only way to find out about your hearing is to visit a professional and let them evaluate you.
We offer a FREE evaluation on a limited basis, please call to make an appointment at least a week in advance due to our busy schedule. There is no obligation, and our highly trained and friendly professionals can discuss the results of your evaluation so you will know what options you might want to consider.