Hearing and Audiology 101 (NDSC info)

If you're like me and had heard the terms but didn't really get it, I'm starting to get a grasp on all of this. I'm still learning, but it's coming.

I posted recently about my frustration about Kamdyn testing in the mild hearing loss range even after tubes. I spoke with the Audiologist on the phone, and she was addressing all of my concerns and questions.  I'm also going to throw in some of the things that we heard at a session on hearing at the NDSC convention.

Hearing tests 101:

OAE
Kamdyn's audiologist said Kamdyn passed the OAE. From what she explained to me, the OAE only determines severe hearing loss. This is why it is used on newborns. It easily tells if the newborn is deaf. Kamdyn still has one done at every hearing test. It tests the function of the cochlea and auditory nerve (inner ear).

Tympanometry
Then, there's the Tympanometry test. This tests the movement of the ear drum. If you've ever heard your child's ear drums are stiff, it means they did not vibrate for this test. If the ear drums do not move, it indicates fluid in the ears, even if there isn't an ear infection. If the child has tubes, like Kamdyn does, this test determines if the tubes are open and functioning properly.  This is especially helpful for children like Kamdyn who have tiny ears, making it hard for the doctor to see in.

   Picture from: The Hearing Specialist

A line curving up shows movement of the ear drum.  A flat line indicates no movement, indicating fluid or a blocked tube.

Behavioral hearing test:
A behavioral test on a child under the age of 5 or 6 is difficult, because they are not able to respond to the test as well as older children.  Remember those hearing tests with the head phones and raising your hand on the side you heard the sound?  That is a behavioral hearing test.  Since that won't work for a baby or toddler, they use the system that we are all too familiar with, where they emit a sound from either the left or right speaker.  When the child responds to the sound, they follow it by a visually stimulating reward (a bright picture or noisy toy). 

I have noticed that when they have another person in the room with us, Kamdyn is more distracted by that person being in there.  She also loses interest quickly, as any child her age would.  The Audiologist also explained to me that young children often have a hard time responding to the lower tones, because they are simply not as interesting.  Why would they want to turn toward that sound, it's boring.  So this test is difficult and not the best at getting accurate hearing results for each ear.  But, at the same time, it is all we have at this young age, and it has been done enough times that there is a system behind it.

Regardless of the trouble with the test, I am going to take it seriously if my child is not evaluated with normal hearing. The audiologist at the NDSC convention stressed the importance of normal hearing for any child. She stated that a typical child with some degree of hearing loss in one ear will likely have to repeat a grade. As a teacher, that sounds like a pretty significant affect to me. With language and speech barriers already in her way, Kamdyn does not need more things, like hearing loss, stacked against her. There is not a standard of hearing loss for a child with Down syndrome. Many children with Down syndrome will be classified at some point with some degree of hearing loss, but it has been proven that the most effective way to address these issues is aggressive and early treatment, whether it's tubes or hearing aids.


Behavioral test results:

At the NDSC session we attended, the Audiologist said that normal hearing was at 15 decibels.  Kamdyn's audiologist considers 20 decibels in the normal range as well.  Before tubes, Kamdyn was in the 30-60 range, mild to moderate hearing loss.  After tubes, she is in the 25-30 range, moderate hearing loss.

Here is a chart similar to the one that we were given at the NDSC convention:

Chart from Cochlear Implant Online

You can print one off for yourself here:  Listen and Talk

ABR:
ABR stands for Auditory Brain stem Response. It measures the electrical activity in the brain as a result of sounds. MedicineNet.com says, "The audiologist can then present different loudness levels of each sound and determine the softest levels at which the infant can hear." An infant is able to do this test while sleeping, but an older child needs to be sedated, because they have to be still for the test.


The plan for Kamdyn:
As for Kamdyn, the plan for her is to have a hearing test in August with a different audiologist (basically a second opinion) that we set up through our pediatrician.  She has a one hour hearing test set up at her usual audiologist/ENT in a few months.  Depending on the results from these, we will decide where to go next.  If we are still not getting normal hearing results, we will most likely pursue an ABR.

My two cents:
I would recommend that you always ask for the exact numbers from the behavioral hearing test.  Print off your own copy of the chart like I pictured above and take it with you.  Know your child's hearing.  And if it's not normal, find out what you are going to do next. 

And like I said, I'm still learning, so if I got something wrong, or I left out something important, feel free to fill me in.  Thanks.