Hear, Hear!

Listening to you, I get the music
Gazing at you, I get the heat
Following you, I climb the mountain
I get excitement at your feet

--The Who, See Me, Feel Me

Last Thursday, amongst two night shifts, two trips to the dentist and getting our ducts cleaned, we took Wyatt to the audiologist.  Like many preemie babies (with and without Down syndrome), he was referred for frequent monitoring of his hearing.  Those with DS are watched especially closely as there are a variety of hearing issues that can occur. He's had his hearing tested several times since birth , starting with our first trip when he was 4 months old (corrected).

Hearing issues are a common problem at birth (about 1-2% in the general population).  Many populations of infants are at high risk;  those amongst the highest include the premature, those with lower oxygen levels at birth, jaundice, irregularities of the head and face, infections, low Apgar scores and conditions such as Down syndrome.

Testing infants, as you can imagine, is a little trickier than testing a larger child or an adult that can easily indicate or describe what they are experiencing.  Also, there is the source of the potential hearing loss to consider;  is it a conduction issue or a sensorineural one?  Luckily, there are two different methods to test hearing in the little ones.  Both are automated, non-invasive and do not require the infant to react to anything.

ABR (or BAEP)

The Auditory Brainstem Response (ABR) or Brainstem Auditory Evoked Potential (BAEP) test monitors electrical impulses between the auditory nerve and key portions of the brain.  Electrodes are placed on the scalp and the activity is recorded as a series of clicks are delivered to the infants ears via small earphones placed in the ear.  Using this test, it can be determined what range of hearing the child has. 

OAE

The Otoacoustic emission test  (OAE) measures a sound bounced back from the inner ear and tests the functioning of the cochlea.  An earpiece containing both a microphone and a sensor is placed in the ear and a series of clicks and tones is measured once it has been processed by the inner ear.  Sounds that are required for understanding speech are tested and based on this criteria, the child either passes or fails. 


Wyatt has always passed with flying colours in his right ear, but his left was presenting with some odd results.  During the OAE, we were either detecting fluid in the inner ear or a small depression on the eardrum itself.  This time, as he is older and now able to be conditioned to a stimulus, we had a new test; he was taught that after he heard a sound, a mechanical toy would light up and play for a few seconds in a shadow box.  Tiny microphones, identical to the ones he wore in his ABR tests, were placed in his ears and he was given some toys to occupy his attention when he wasn't being tested.  He loved this test, was conditioned after two tries (!) and passed with flying colours.  So much so that he has been discharged from the high risk program at Erin Oak and will only have to return if we encounter problems (such as suspected damage from ear infections, etc). 

We were happy to get this news;  not only is it one less appointment to worry about, but knowing that his hearing is perfect and speech ready is a weight off our shoulders.  We kinda knew that anyway... That kid could hear a cookie wrapper opening in the next room with the radio on and his brother and sister noisily tearing about the place.  However, now we know his hearing will not hamper his language development.  Which is important, as I long for the day that he can finally say (using a word or sign) "Mama".

----------------------
Hyde, M., Newborn Hearing Screening Programs: Overview, The Journal of Otolaryngology, 34:2, August 2005.

Mersch, J., Kibby, J., Newborn Infant Hearing Screening, MedicineNet, 2012

Special Thanks to:

Infant Hearing Program, Mount Sinai Hospital, Toronto.

Erin Oak Centre for Treatment and Development, Ontario.