Deaf like daddy
Tuesday, 31st July 2007 by tom
We took Jon to Charing Cross hospital yesterday to have a hearing test, following his dubious results in the hearing screening at Queen Charlotte’s.
It turns out he has normal hearing in his left ear (praise the Lord) and 70db to 90db loss in his right ear across the audible spectrum. This means that the quietest sounds Jonathan can hear in his left ear are 10 million to 1 billion times louder than the quietest sounds humans can normally hear.
This sounds quite extreme, but the full range of human hearing between the quietest sound we can hear and the pain threshold is vast. We can hear sounds 10 trillion times quieter than the loudest we can bear. This means Jonathan does actually have some useful range in his right ear that could be realised with a hearing aid. Although it would have to be a pretty powerful one – his deafness counts as “severe”, just below the highest level of “profound”.
All this is pretty academic, though. It is most likely that his hearing loss will just not bother him very much. This has been the experience of quite a few people in my family, including me, who have serious hearing loss in the right ear. A hearing aid may be useful to help him manage noisy environments, which is the one place I do struggle a little.
For those interested in the hearing test itself, it is called an ABR test, Auditory Brainstem Response. It has to be done while the baby is peacefully asleep because it relies on detecting EEG signals in response to sounds they play through his ears. It’s rather clever really and while not as good as an audiogram where the subject consciously responds to sounds, it isn’t far off.
