Reader’s Choice 2014: Fun Facts about Hearing Loss

Dear Readers:
During this holiday season, the editors at Hearing Health & Technology Matters (HHTM) are taking some time off. However, we are not leaving you without anything to read on our blog this week. Instead, we are publishing a special holiday edition filled with what we call our Readers’ Choices.
HHTM has had more than half a million page views in 2014, and the Readers’ Choices featured this week are the posts published on each of our individual blogs that drew the largest number of viewers during the year.
Whether or not you have read these Readers’ Choice posts before, we think you will enjoy them. And be sure to return next week when all of us editors, our batteries recharged, will publish a New Year’s Eve issue filled with fascinating new posts to get 2015, HHTM’s fifth year, off to a great start.

Here are two Readers’ Choices for Hear in Private Practice:

 

The American Academy of Audiology and Hearing Loss Association of America have put together in separate documents some interesting facts about hearing loss. Beth Benites, AuD, compiled a list to bring some of these facts to our attention. They can be used for all ages!

1. Sitting close to loudspeakers at concerts (which can reach about 120 decibels) can damage your hearing in just 7.5 minutes!
2. At the age of 65, one in three adults has some hearing loss; however, a majority of the people who suffer from hearing loss are under age 65.
3. Hearing loss is the third most common health problem in the United States.
4. Excessive noise exposure is the #1 cause of hearing loss.
5. The bones in the middle ear (malleus, incus, and stapes) are the body’s smallest bones. All three can fit together on the surface area of a penny.
6. 37% of children with hearing loss fail at least one grade.
7. The outer ear never stops growing throughout one’s lifetime.
8. The middle ear is about the size of an M&M.
9. The inner ear is no larger than a pencil eraser in circumference.
10. Not all living creatures hear with ears. Snakes use jawbones, fish respond to pressure changes, and male mosquitoes use antennae.
11. The eardrum moves less than a billionth of an inch in response to sound.
12. In World War I parrots were kept on the Eiffel Tower in Paris because of their remarkable sense of hearing. When the parrots heard enemy aircraft,  they warned everyone of the approaching danger long before any human ear would hear it.
13. Sometimes if you have damage to your ears, your perception of taste may be off because the nerves (called the Chorda Tympani) run through the ear and connect the taste buds on the front of your tongue to your brain. Sometimes people who have had ear surgery experience a change in their sense of taste. It does not mean that hearing loss directly correlates to an inability to taste.
14. Ear infections are more common in children because of their developing immune systems and differences between their Eustachian tubes (at more of a horizontal angle) than those of adults.
15. Earwax has been useful to anthropologists for studying mankind’s early migratory patterns.

 

IN FITTING HEARING AIDS, BE VERY CAREFUL WHEN YOU AMPLIFY THE LOW FREQUENCIES

 

By Robert L. Martin

If you are new to audiology, be careful when you read this article. Today I want to tackle an advanced concept, so you need to have considerable experience and well-developed intuition when you attempt to employ these ideas.

Listed below are hearing thresholds for six patients. For the sake of simplicity I’m showing you their hearing thresholds for only ear (their hearing is the same in both ears). Also, for simplicity, I am showing thresholds for the five standard five test frequencies (250, 500, 1000, 2000, and 4000 Hz):

Let’s assume we have already established a standard listening program for these patients. We’ll call it the “default” program or Program 1. Now, let’s consider what happens if we add substantial low-frequency amplification (go bass heavy) or if we subtract substantial low-frequency amplification (go bass light).

 

SIX PATIENTS, CASE BY CASE

The first patient has good hearing in the lower frequencies, so I see no reason to go bass heavy with her. She is an excellent candidate for an open fit (a naturally bass light fitting).

The exception to this logic is a hard-of-hearing infant. In fitting a baby, we need to give the child the very-low-frequency rhythm and intonation cues inherent in speech in the zone of 100 to 300 Hz to allow for development of normal language abilities. My old professor at the University of Tennessee, Dr. Carl Asp, would say all hard-of-hearing children need extra-wide-band amplification so they not only assimilate the articulated aspects of speech but also its emotional content.

If Patient 2 is an adult who has not previously worn hearing aids, you will probably give him an open fitting. However, bear in mind that no truly open-fitted aid can give a patient significant amplification in the lower frequencies, because low-frequency sound escapes easily through any type of opening. So, an important aspect of this fitting is designing a fitting program with the patient: open fitting the first 1-4 months, followed by the addition of earmolds to modify this into an occluded fitting, which lets you add substantial amplification to the lower frequencies. This approach makes this new hearing aid wearer happy initially, then helps him get greater benefits once he becomes used to amplification.

Patient 3 and 4 both have “reverse curve” hearing loss configurations. Going bass heavy with these patients is an approach I would recommend only to highly experienced practitioners. When you start adding too much gain in the lower frequencies, you quickly get into an “upward spread of masking” situation, which results in deterioration of sound quality and word understanding. To my experienced peers I would say, “Adding low-frequency gain is like adding salt to your vegetable soup; you need some salt, but be very, very careful how much you add.”

Since Patient 5 and 6 both have very poor hearing, a wide-band response will probably work best. Once again, caution and skill are needed and you must pay a lot of attention to the amounts and type of compression you use.

One last thought. We don’t tend to measure and consider hearing at 125 Hz, yet this is a very important frequency for some patients (patients #5 and #6, for example). If you are considering adding significant amplification in the lower frequencies, it pays to measure the threshold in that zone.