Download Anatomy of the Ear

Hearing Loss
Basic Audiology
Information
By El Eshun
Anatomy of the Ear
1. Outer ear 2. Middle ear 3. Inner ear 4. Central hearing
Anatomy of the Ear
Auditory processing
Difficulties
Anatomy of the Ear
Auditory
neuropathy/dysynchrony
Anatomy of the Ear
Sensorineural Hearing
Loss
Anatomy of the Ear
Conductive Hearing Loss
TYPE
 CONDUCTIVE
 SENSORI NEURAL
 RETROCOCHLEAR
 MIXED
 PROGRESSIVE
 BILATERAL
 UNILATERAL
 HIGH FREQUENCY
 SLOPED
Degrees of Hearing Loss
 Normal – 0-20 dB
 Mild - 21-40 dB
 Moderate - 41-55 dB
 Moderate – Severe – 56-70 dB
 Severe – 71-90 dB
 Profound – 91+ dB
Audiological Assessments
 Otoscopy
 Tympanometry
 Audiometry
 Auditory Brainstem Response (ABR)
 Otoacoustic Emissions (OAE’s)
•Otoscopy is an examination that involves looking into the ear
with an otoscope in order to examine the 'external auditory
canal‘ , the outer ear and the ear drum
•The outer ear is inspected for signs of disease that may relate
to the symptoms.
•Abnormal findings of the outer ear may include:
eczema. (otitis externa). wax obscuring the eardrum.
Something lodged in the ear
Examination of the eardrum
The normal eardrum appears pinkish-grey in colour and is
approximately circular in shape.
 abnormal findings seen with the otoscope include
a hole (perforation) in the eardrum,
acute infection of the middle ear (acute otitis media).
Sometimes in acute otitis media the eardrum will burst, allowing the
pressure (and the pain) to reduce. Then one can often see the tear in
the drum as well as the discharge in the outer ear. In the majority of Inserted grommet
people such a tear will heal completely.
 Otoscopy
 Tympanometry
 Audiometry
 Auditory
Brainstem Response (ABR)
 Otoacoustic
Emissions (OAE’s)
Tympanometry
 Tympanometry or immittance Audiometry is used to
check the movement of the eardrum.
 Tones are "bounced" off the ear drum/tympanic
membrane to determine the amount of sound that is
reflected back through the ear canal.
 If the tympanic membrane is very stiff (eg. with
middle ear effusion) then a lot of the sound is
reflected back. When the tympanic membrane moves
normally, very little of the sound is reflected.
Tympanometry in the Audiological
Report
The pink boxes indicate
whether it is a normal
tympanogram if the peak
falls within the box then
the trace is normal
The 5 most common Tympanograms
Normal Tympanogramnormal mobility and middle ear
pressure
Reduced TM mobility and normal
ME pressure; consistent with
presence of otosclerosis.
Represents stiff ME system.
Hypermobility of eardrum and
normal ME pressure; consistent
with flaccid eardrum or
disarticulation of ossicular chain.(3
bones of the middle ear)
Reduced TM mobility; consistent with
presence of fluid in the middle ear
space.
Normal eardrum mobility and negative
Middle Ear pressure means that the
eardrum is sucked in (retracted);
consistent with eustacian tube
dysfunction.
 Otoscopy
 Tympanometry
 Audiometry
 LINGS
 Auditory
Brainstem Response (ABR)
 Otoacoustic
Emissions (OAE’s)
AUDIOGRAM
A standard way of representing a
person's hearing loss or level.
Most audiograms cover the limited
frequency range 100Hz to 8000Hz
(8kHz) which is most important for
clear understanding of speech.
They plot the threshold of hearing
relative to a standardised curve that
represents 'normal' hearing, in dBHL.
A sound is played at a range
of frequencies and loudness
levels and the client must
show some type of reaction
to indicate that the sound has
been detected
Pure tone audiometry – When you hear a sound press a button to confirm this
Conditioned play audiometry – when you hear the sound e.g put the man in the boat
Visual reinforcement Audiometry – the sound is initially played together with the
appearance of a toy then alone and childs seeking behaviour for the toy is recorded
Behavioural observation Audiometry – spontaneous reactions are watched in
With hearing aids
Right ear air conduction
Left ear air conduction
Listening through the
bones of the skull
therefore bypassing
the middle ear
Listening with
hearing
aids/implant with
speakers
Listening through
headphones or
insert phones
Bone conduction –
not ear specific
represents both ears.
Always measured at
these frequencies only.
Any lower and the child
is responding to
vibrotactile stimulation
(vibration)
Results indicate a
moderate -severe
sensorineural loss
binaurally (both ears)
Hearing levels
with aids showing a
mild to moderate loss
Right ear air
conduction –
showing a
profound
hearing loss
Tympanometry
Normal ear canal volume in children is
between 0.2-2cm3
Compliance (movement)
Maximum compliance of the middle ear
system occurs when the
pressure in the middle ear space is
equal to the pressure in the
Outer ear canal. The maximum
compliance value occurs at
the highest peak of the curve on a tymp
graph . Child max norm = 0.2-0.9ml
Normal middle ear pressure in children
is between +200 and -400 dPA
Left ear air
conduction
showing a sevprofound hearing loss
The arrows indicate that
thresholds (point of
detection) could not be
measured at these
frequencies
Most audiograms
will have a key
explaining what
the symbols on the
audiogram
represent
 Otoscopy
 Tympanometry
 Audiometry
 LINGS
 Auditory
Brainstem Response (ABR)
 Otoacoustic
Emissions (OAE’s)
Lings
 EE, OO, AAH, S, SHH, M
 Detection
The 6 sounds that are
distributed across the
frequencies for speech
Initially the aim is for your child to
show they heard these sounds at
normal conversational loudness
levels then more quieter levels
 Discrimination
Once your child can detect them all
they then need to be able to tell the
difference between the sounds
 Identification
Lastly your child should tell you which
sound is being presented
 Otoscopy
 Tympanometry
 Audiometry
 LINGS
 Auditory
Brainstem Response (ABR)
 Otoacoustic
Emissions (OAE’s)
ABR
 The ABR test is a useful tool for measuring hearing when
other hearing tests cannot be used.
 The ABR test is reliable, objective, non-invasive and
painless. Brain wave activity in the listening centers of the
brain is recorded in response to a series of clicks
presented to each ear. The ABR test indirectly estimates
the level of hearing in the middle ear and inner ear.
 Because of the nature of this testing procedure, the ABR
test does not rely on any form of subjective response from
your child.
ABR is used:
 as a screening procedure for newborns who are at risk for




hearing loss.
as a diagnostic tool to identify infants and small children with a
hearing loss.
to estimate hearing levels in difficult to test patients, i.e.,
children with significant learning difficulties, autistism, children
with developmental delay.
to evaluate children with suspected retrocochlear causes. Ie
Auditory neuropathy and Auditory Processing Difficulties
to evaluate patients with Meniere's disease or similar
disorders.
PROCEDURE
 The ABR test is performed on an individual who is resting





quietly or in a sleep state.
A series of clicks are presented to each ear through special
earpieces inserted into the ear canals.
The audiologist can vary the intensity of the clicks.
The individual wears a headband which records appropriate
brain wave activity.
The averaging computer in the ABR unit then analyzes the
information and it is compared to normal responses.
This procedure does not cause any discomfort to the person.
The test takes approximately one to two hours
 Otoscopy
 Tympanometry
 Audiometry
 LINGS
 Auditory
Brainstem Response (ABR)
 Otoacoustic
Emissions (OAE’s)
An otoacoustic emission (OAE) is a sound which is generated
from within the inner ear. Their existence was first
demonstrated experimentally by David Kemp and they have
since been shown to arise by a number of different
mechanisms within the inner ear. Numerous studies have
shown that OAEs disappear after the inner ear has been
damaged, so OAEs are used in the clinic as a measure of inner
ear health.