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Audiology
Training Course
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Configuration of the ear
①
②
③
④
⑤
Pinna
Ear canal
Eardrum
Malleus
Incus
⑥Eustachian tube
⑦Stapes
⑧Semicircular canals
⑨Cochlea
⑩Auditory nerve
Configuration of the ear
The outer ear consists of the pinna, or auricle, and the ear canal
(external auditory meatus). The pinna – the part of the "ear" that
we see on each side of our heads – is made of cartilage and soft
tissue so that it keeps a particular shape but is also flexible. The
pinna serves as a collector of sound vibrations around us and
guides the vibrations into the ear canal. It helps us decide the
direction and source of sound.
Configuration of the ear
The middle ear begins with the eardrum at the end of the ear
canal. The middle ear contains three tiny bones, called the
ossicles. These three bones form a connection from the
eardrum to the inner ear. As sound waves hit the eardrum, the
eardrum moves back and forth causing the ossicles to move.
As a result, the sound wave is changed to a mechanical
vibration.
The inner ear contains the sensory organs for hearing and
balance. The cochlea is the hearing part of the inner ear. The
semicircular canals in the inner ear are part of our balance
system.
malleus
acoustic wave
pinna
ear canal
incus
stapes
eardrum
outer ear
footplate at
oval window
middle ear
Air-conduction
endolympha and
perilympha in cochlea
auditory sense
cortis'
comprehensive analysis
nerve impulse
Degrees of hearing loss
Between “hearing well” and “hearing nothing” lies a wide range
of different degrees of hearing loss. Experts distinguish
between mild, moderate, severe and profound hearing loss.
Most cases of hearing loss are categorized as mild or
moderate.
Degrees of hearing loss
The sound of speech
Human speech consists of vowels
and consonants at different loudness
and frequency levels. They are
recorded on the audiogram as a socalled “speech banana”. It is an easy
way to check whether the entire
spectrum of speech is still audible
and how a person’s hearing changes
with time.
Degrees of hearing loss
Mild hearing loss (25-40dB)
Soft noises are not heard. Understanding speech is difficult in a loud
environment
Moderate hearing loss (41-60dB)
Difficulty understanding speech, especially in the presence of background
noise. Higher volume levels are needed for hearing TV or radio.
Severe hearing loss (61-80dB)
Conversations have to be conducted loudly. Group conversations
are possible only with a lot of effort
Profound hearing loss (>81dB)
Some very loud noises are heard. Without a hearing aid,
communication is no longer possible even with intense effort
Types of hearing loss
Conductive Hearing Loss
This type of hearing loss is caused by problems in the ear canal
and/or the structures in the middle ear. It occurs when sounds from
the outside world cannot be transmitted normally through the ear
canal and/or middle ear to the inner ear.
The most common causes of conductive hearing loss can be a
buildup of wax in the ear canal, perforated eardrums, fluid in the
middle ear (common in children), or damaged or effective ossicles
(middle ear bones).
A person with conductive hearing loss may notice their ears seem to
be full or plugged. Most conductive hearing losses can be medically
or surgically treated. If, for some reason, the hearing loss cannot be
corrected, hearing instruments can provide benefit.
Types of hearing loss
Sensorineural Hearing Loss
This type of hearing loss is the most common type of hearing loss.
More than 90 percent of all hearing instrument wearers have
sensorineural hearing loss.
It results from a combination of problems in the inner ear and the
auditory nerve. They then become unable to convert sound vibrations
into the electrical signals needed by the auditory nerve.
The nerve pathways in the auditory nerve itself can also become
damaged, preventing the signals from reaching the brain. Although
this damage can be caused by exposure to loud noise - through
working in a noisy environment for too long - the primary reason is
aging.
People with sensorineural hearing loss typically report they can hear
people speak, but can't understand what they're saying. Hearing
instruments and assistive devices can help.
Types of hearing loss
Mixed Hearing Loss
This kind of hearing loss is caused by a combination of
problems in the middle and the inner ear or the auditory
nerve. For example, the person may have a noise induced
hearing loss from noise exposure and a perforation in the
eardrum. The combination of sensorineural and conductive
hearing therefore the loss is mixed.
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