What is Deafness?
In this section, you will be reading about what deafness is, and what it is all about, so, hopefully by the end of this section, you will have gained a little bit more knwoledege to what deafness actuallty is.
What is hearing loss?
The level of a person's hearing ability is measured on an audiogram like this on the side here. It maps out the loudness of sound in dB and the pitch of sound in Hz. When a person is considered to have "normal" hearing, it means that they can hear 20 dB or less in both ears, but if a person is considered "Deaf" or "Hard of Hearing," it means that they cannot hear 20dB in one or both ears. On this audiogram, "normal" hearing is above the 20 dB line at the top. The blue patch that you can see on there is called the "speech banana", that is the zone where our speech sounds are, and all of those random objects just floating around actually have a lot of meaning to them. They are the objects that show you the typical loudness and pitch of those sounds. The more hearing loss you have, the lower the sound you'll be able to hear.
When a person has their hearing tested, it is mapped on an audiogram like this. As you can see, there are two lines, those lines are where the person's hearing is at; the red line is the left ear, and the blue line is the right ear. What this audiogram is telling us, is that the person cannot hear anything above those lines. That grey patch that you are seeing, is the same as the previous image, the speech banana, which is where the "normal" speech sounds occur. so as you can see, the audiogram that belongs to this person, they can hear virtually nothing, and is missing out on all speech.
The ear is made up of four parts.
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The outer ear ; the part that everyone sees on the side of our heads (pinna), the ear canal and the eardrum
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The middle ear ; this includes three small bones (ossicles) that send the movement from the eardrum to the inner ear
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The inner ear; is made up of a small snail shaped organ for hearing (cochlea), semi-circular canals that help with the balance, and nerves that go to the brain
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Auditory Nerve; is the hearing system pathway to the brain
Hearing works like this...
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Sound travels through our outer ear (pinna) and down the ear canal, striking the eardrum causing it to vibrate
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Vibrations from the eardrum cause the ossicles to vibrate. These are the three smallest bones in our body. This creates movement of tiny hair cells in the inner ear. "
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The movement of the hair cells sends an electrical impulse through the auditory nerve to the hearing centre of the brain, which translates them to sounds to the brain can recognise.
How does hearing work?
Are you born deaf or does it happen over time?
BOTH CAN HAPPEN!!
Hearing loss at birth is called a Congenital hearing loss, and hearing loss after birth is called an Acquired hearing loss.
C0NGENITAL HEARING LOSS
ACQUIRED HEARING LOSS
What causes hearing loss?
There are many things that can cause hearing loss, for example:
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Damage to the inner ear
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Growing old
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Diseases
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Loud noises
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Build up of ear wax
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Unusual bone growths
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Ear infections
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Tumours
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Ruptured eardrums
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Generic defects
Two main types of hearing loss
A Conductive hearing loss is where the sounds can't get past the outer ear and middle ear. For this hearing loss, soft sounds may be hard to hear and loud sounds may be muffled. Medicine or surgery can fix this hearing loss.
A sensorineural hearing loss is where the deafness is located in the inner ear, the deafness can be caused by damaged hair cells and nerves, damage to the vestibulocochlear nerve, or damage to the brain central processing centre. For this deafness, nothing can cure the deafness, but you can get cochlea implants if eligible.
Can you have both types of hearing loss?
YES
A mixed hearing loss is where a conductive hearing loss can also happen at the same time as a sensorineural hearing loss. This means that there is damage to the outer ear or middle ear, and there is also damage to the inner ear or nerve pathways to the brain.
This is the type of hearing loss that I, personally have.
When I was younger, the conductive hearing loss made it hard for the doctors to diagnose my sensorineural hearing loss. The doctors had to address the issues in the outer ear (with grommets and reconstructive surgery) before the issues in the inner ear could properly be diagnosed and addressed.
How do hearing aids work?
Hearing aids are most effective for people with conductive hearing loss or those with a mild sensorineural hearing loss. That is because they amplify the sound into the outer ear. This means they are not very effective for people with moderate, severe, or profound hearing loss.
They work by sending sound through a three part system: The microphone sound and converts it into a digital signal. The amplifier increases the strength of the digital signal. The speaker produces the amplified sound into the ear.
There are three main types of hearing aids - 1. Behind the ear, 2. In the ear, 3. In the canal. Basically, the more severe the hearing loss, the bigger device you'll need
How do cochlear implants work?
Cochlear implants are most effective for people with a moderate, severe, or profound hearing loss. They cannot be used for conductive hearing losses.
There is a long assessment process to work out if cochlear implants are suitable for you. It takes about 12 months.
They use a sound processor placed behind the ear. The processor picks up the audio signals and sends them to the receiver implanted underneath the skin behind the ear. The receiver sends signal's to electrodes implanted in the snail-shaped organ in the inner ear (cochlea).
