the ear. external ear we have an ear on each side of our head. noise is collected by the outer ear...
TRANSCRIPT
THE EAR
External Ear We have an ear on each side of our head. Noise is collected by the Outer Ear or pinna (the flaps which stick out from the sides of your head and come in all shapes and sizes!).
Ear Canal The sound waves travel along the Ear Canal to the ear drum. Did you know that the ear canal is lined by 4000 wax glands which secrete ear wax or cerumin to trap dirt, dust or bugs and protect the ear drum?
Ear Drum When the sound waves hit the Ear Drum they make it vibrate. The ear drum is stretched across the entrance to the Middle Ear and provides an airtight seal
3 Tiny Bones: The Hammer, Anvil and Stirrup are the smallest bones in your body. Vibrations by the ear drum cause the 3 bones to vibrate in turn. As the last (the stirrup) vibrates, it causes vibrations in the fluid of the cochlea.
Inner Ear The Cochlea (snail shell) is about the size of a pea. The mechanical vibrations in the fluid of the cochlea bend the thousands of tiny delicate Hair Cells, which change the vibrations into electric nerve impulses.
Outer hair cells are contracting in response to electrical stimulation
Nerve fibers are moving in response to electrically evoked outer hair cell contractions
Hearing Nerve The Hearing Nerve then carries these electric impulses to the brain.
The Brain: The Brain translates the sounds it receives so that they have meaning for us. Isn't that all pretty amazing and worth looking after?
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Who tests your hearing?
AUDIOLOGIST• Administers a variety of tests such as air and bone conduction, speech
reception and discrimination tests to determine type and degree of hearing loss, site of damage and effect on comprehension and speech.
• Outside of the school district, audiologists can fit people with hearing aids and cochlear implants.
• Within the school district an audiologist can check & troubleshoot problems with hearing aids/cochlear implant. An Educational Audiologist can set up and trouble shoot FM or speaker equipment.
• Audiologists consult with physicians and other professionals to obtain additional student information. They also can make suggestions in treatment programs.
• Serve as a consultant to classroom teachers and participate in meetings (IEP and evaluation).
What is an audiogram?
Audiogram
audiogram — a chart that shows how well you hear. An audiogram uses decibels — a way of measuring sound — to show how well you hear. Soft sounds don't have as many decibels as loud ones. Your audiogram would show you how many decibels you can hear.But hearing is about more than loud and soft sounds. It's also about frequency or pitch. That can be a little hard to understand, but think of it as the kind of sound it is. For instance, a metal whistle might make a high-pitched sound and a tuba might make a low-pitched one. Just like a piano's keyboard, the pitches are low on the left side (125 or 250Hz), and then gradually climb to higher pitches on the right side (8000Hz). Your audiogram also would show how well you hear at different pitches.
PITCH
Perception of high frequency sounds:• Different frequencies cause larger vibrations at
different locations along the basilar membrane.
• High frequency sounds causes maximum vibrations near the stirrup end of the basilar membrane.
• Lower frequency sounds cause maximum vibrations at the other end
• Pitch
This is how high or low a sound seems. A bird makes a high pitch. A lion makes a low pitch.
• Sounds also are different in how loud and how soft they are. The more energy the sound wave has the louder the sound seems. The intensity of a sound is the amount of energy it has. You hear intensity as loudness.
Remember the amplitude, or height of a sound wave is a measure of the amount of energy in the wave. so the greater the intensity of a sound, the greater the amplitude.
WHAT IS AN AUDIOMETER?
Hearing EvaluationIf your audiologist wants to do hearing tests, he or she will need your help. These tests are done to see how good — or poor — your hearing is in each ear. You'll probably wear earphones and listen for different sounds. You might even go into a special soundproof booth to do this test.
Hearing levels are obtained and marked for most of the pitches across the audiogram. An O is used for the right ear and an X is used for the left ear to represent the air thresholds. When a bone-conduction vibrator is used to test for thresholds, a < symbol is used for the right ear and a > symbol is used for the left ear. A bone-conduction vibrator is a device that gently rests on the mastoid process of the skull (the bone behind the ear) and is held in place by a small metal band stretching over the top of the head. This device transmits sound via direct vibration of the bone. The vibrations are carried through the bones and tissues and fluids within the skull directly to the cochlea (the hearing organ of the inner ear). This process allows the examiner to bypass the entire outside and middle ear areas and test the sensitivity of the inner ear directly. The audiologist also might have you listen to words and repeat them.
• By comparing the headphone thresholds with the bone vibrator thresholds at each pitch, we can determine if a hearing loss is conductive, sensorineural or mixed. If the air conduction thresholds show a hearing loss but the bone conduction thresholds are normal, then we call it a conductive hearing loss. If both the air conduction thresholds and the bone conduction thresholds show the same amount of hearing loss, we call it a sensorineural hearing loss. And finally, a mixed hearing loss is when the bone conducted thresholds show a hearing loss and the air conducted thresholds show an even greater hearing loss.
• Thus, when the hearing test is completed, the person should be able to tell how well they hear at low, medium and high pitches. If a hearing loss is present, they should also be able to tell which part of the hearing mechanism (the outside, middle or inner ear) is causing the loss
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Conductive hearing lossThis is caused by anything that stops sound moving from your outer ear to your inner ear. The following are possible causes of conductive hearing loss.
• Middle ear infections (acute otitis media). Collection of fluid in the middle ear - 'glue ear' (otitis media with effusion). • Blockage of the outer ear, usually by wax. • Otosclerosis, a condition where the ossicles of the middle ear
harden and become less able to vibrate. • Damage to the ossicles, for example by serious infection or head
injury. • Perforated (pierced) eardrum, which can be caused by an
untreated ear infection (chronic suppurative
This audiogram shows a conductive hearing loss in the left ear. The white area represents the sounds that the person would not hear (softer then their thresholds) and the tan area indicates all of the sounds that the person would be able to hear (louder then their thresholds).
Sensorineural Hearing Loss
Sensorineural hearing losses occur when the "inner" ear or the actual hearing nerve itself becomes damaged. About 90% of all people with hearing impairment are in this category, making it the most common type of hearing impairment. Thus, "sensorineural" indicates the part of the ear that is malfunctioning and encompasses many different causes for the malfunction. This type of hearing loss is frequently not medically or surgically treatable. It is typically permanent and irreversible. However, most people with sensorineural loss find wearing hearing aids to be of significant benefit and some people with severe loss can benefit from a cochlear implant
This audiogram shows a sensorineural hearing loss in the left ear. The white area represents the sounds that the person would not hear (softer then their thresholds) and the tan area indicates all of the sounds that the person would be able to hear (louder then their thresholds).
This audiogram shows a mixed hearing loss for the left ear. The white area represents the sounds that the person would not hear (softer then their thresholds) and the tan area indicates all of the sounds that the person would be able to hear (louder then their thresholds).
Mixed Hearing Loss Mixed hearing losses are simply combinations of the above two types of hearing loss. They can occur when a person has a permanent sensorineural hearing loss and then also develops a temporary conductive hearing loss.
The audiogram shows hearing thresholds within normal ranges for the left ear. The white area represents the sounds that the person would not hear (softer then their thresholds) and the tan area indicates all of the sounds that the person would be able to hear (louder then their thresholds).
Tympanogram
Tympanic membrane is the fancy name for eardrum, so when a doctor wants to find out how your eardrum is working, he or she may get a tympanogram.
In this test, a doctor uses a special machine that is small enough to be inserted into you ear. It makes a quiet noise that should get your eardrum
moving. The result of this test is known as a tympanogram
