The world of hearing loss is a bit vague and fuzzy to most people. In my short experience, when we tell someone that Alex or Luke has a hearing loss they assume that they are completely deaf. Actually, you don’t really use the word deaf. Well, you can if you want. But, a ‘deaf’ person suffers from a profound hearing loss. See, you’re learning something already. Maybe. (Click here to read more about understanding hearing loss.)
If you are interested in what is going on with Luke, you’ll need a little base knowledge. I’m going to attempt to give you that. I am not a doctor or an audiologist. I’m just a parent who’s trying to educate myself in order to help my child. Fasten your seatbelts.
A person’s range of hearing can be charted over several frequency bands. The frequency (Hz), or cycle per second, a sound is determines the pitch of the sound. For example, a low frequency sound has a low pitch – think of a man’s voice. A high frequency sound has a high pitch – a woman’s voice. Sounds are also composed of a loudness factor, or decibel (dB). The lower the decibel, the softer the sound – ie, leaves rustling. The higher the decibel, the louder the sound – an airplane engine or lawn mower. An audiogram tests at which decibel level an individual is able to hear each frequency band, for each ear. So, for the right ear, a person might be able to hear 250 Hz (frequency range) at 15 dB (decibel), but 500 Hz at 20 dB. A person could have normal hearing in some ranges and have a profound loss in others. One ear could have a profound loss in all ranges, while the other ear has normal hearing in all ranges. It’s not usually simply that you can hear or you can’t – it’s more involved. Are you still following?
For your viewing pleasure, I’ve attached a sample audiogram. Children are considered to have normal hearing if they can hear every frequency range at 15 dB or lower. The orange dashed line represents normal hearing for children. Normal hearing for adults is considered to be 25 dB or lower for all ranges. The audiogram below shows where typical sound lies – water dripping, birds, normal speech, dogs barking, etc. What gets even crazier is that the particular sounds that make up speech can be plotted on the audiogram. For example, vowels tend to be lower in frequency and louder, while consonants are higher frequency (particularly s, f, and th). The words along the right side represent the severity of the hearing loss. Luke is considered to have a mild/moderate loss.
The results of an individual’s hearing test (which is done in a sound proof booth) is plotted on an audiogram – ‘X’ represents the left ear, ‘O’ represents the right. Lines are drawn between the ranges to illustrate the line of hearing. Anything below the line can be heard, while anything above cannot. If you look at Luke’s line on the above audiogram, he can hear dogs barking and the vacuum cleaner, but can’t hear water dripping or birds tweeting. What’s even more important is that his loss cuts through the normal speech range, so he’s missing a large amount of language. To add to that, he isn’t able to hear complete words (all the letters and sounds of a word). You can imagine that learning to talk, listen, read, and write would be exceedingly hard if you can’t hear everything. That’s why getting help (ie – hearing aids and therapy is so vital). Overall, Luke is hearing quite a bit – and for that we are so, so thankful.
Reasons for Hearing Loss:
There are several factors that can lead to hearing loss. Age, prolonged exposure to high noise, medicine, neurological disorders, trauma, illness, and genetics are all potential causes of hearing loss. The majority of hearing loss in children is a result of their genetics. This is the case for Luke. There’s a strong family history of hearing loss in Alex’s family. Alex has a hearing loss that was diagnosed at age 4. He also wears hearing aids. Although it hasn’t been confirmed, it is highly likely that Luke loss is genetic.
Types of Hearing Loss:
Hearing loss can be classified into two types: conductive and sensorineural. Conductive hearing loss occurs when the sound isn’t able to reach the inner ear due to a malfunction or malformation of the structures that make up the ear and inner ear. Scar tissue from repeat ear infections would be an example of conductive hearing loss. Conductive hearing loss is often referred to as a mechanical hearing loss, and sometimes can be corrected with surgery.
Sensorineural hearing loss occurs when there is damage for dysfunction in the cochlea, the nerve that transmits impulses from the cochlea to the brain, or in the area of brain responsible for speech. Sensorineural hearing loss cannot be corrected with surgery and is considered to be permanent.
An audiologist can determine the type of hearing loss using bone conduction. During a hearing test, the individual will wear a baha device that vibrates the bone behind the ear. If the person is able to hear better with the baha, they generally have a conductive hearing loss. If the loss is the same, it is considered sensorineural.
A person can have conductive and sensorineural hearing loss, also known as mixed hearing loss. If only one ear has a loss, it is considered unilateral. If both ears have a loss, the person has a bilateral hearing loss.
Luke has a mild-to-moderate, bilateral sensorineural hearing loss across all ranges.
Obviously this just scratched the surface of the fine field of audiology. I’m hoping that I provided you with a little bit of a knowledge base so that my ramblings will make sense. Now, here’s your award for reading this and staying awake! *high-five!*