The document discusses the anatomy and physiology of the ear and hearing process. It describes the three main parts of the ear - outer, middle, and inner ear. It explains how sound is conducted through the ear canal to the cochlea, where it is transduced into neural signals and transmitted to the brain. The document also discusses types of hearing loss and common causes. Additionally, it provides an overview of how hearing aids work and the different styles available.
2. To distinguish between the two types of
deafness
To know the proper method of performing
the Rinne and Weber tests
3.
4. In doing the experiment there are two tests that we should
perform. First is the Rinne test. From our group we chose the
representative to whom we would perform the experiment.
One ear of the subject was plugged. On the heel of the hand, a
tuning fork was set in motion by striking it. At the level of the
upper portion of the unplugged ear canal, the stem of the
tuning fork was placed on the mastoid processes. When the
sound from the vibrating fork disappears, the subject was
asked to make a signal. Then, place the line of the fork in front
of the unplugged ear at a distance of 3 to 6 inches. Whether
the subject hears any sound or not indicate it. The procedure
was repeated on the other ear.
5. For the next test which is the Weber’s test,
another member of the group was selected to
be the subject. On the heel of the hand, the
tuning fork was strike. On the forehead of the
subject the stem of the tuning fork was
placed. We asked the subject to compare the
sounds that was heard in each ear. We
indicate whether the sound was heard
equally or not.
6.
7. Outer ear – pinna, external auditory canal
Middle ear – tympanic membrane, three
ossicles and the Eustachian tube
Inner ear – cochlea, semicircular canals,
nerves
* All three parts are involved in hearing
while for vestibular functions, the inner ear
is the only one involved.
8.
9. 1. Pinna/auricle/earlobe – funnels the sound
waves into the ear
2. External auditory canal – passageway of
sound to the middle ear; lined with hair
3. Eardrum/tympanic membrane – transmits
sound from the outer ear to the ossicles
4. Malleus, incus, stapes – three small bones of
the ear
5. Eustachian tube – equalizes the pressure in
the middle ear and the throat
10.
11. 6. Cochlea – organ of hearing; Lt. for “snail
shell”; has Organ of Corti
▪ Scala tympani
▪ Scala vestibuli
▪ Scala media
7. Semicircular canals – three (anterior, lateral,
posterior); for balance
8. Vestibule – central part of the bony labyrinth
12. Malleus faceplate of stapes (3/4 of the
amplitude of movement)
Surface area of tympanic mem. : 55 sq. mm.
Surface area of stapes: 3.2 sq. mm.
22 TIMES MORE PRESSURE ON THE FLUID.
13. Reduces the intensity of the sound by as
much as 30-40 decibels
Latent period of 40-80 ms
Stapedius – pulls stapes outward
Tensor tympani muscles – pulls malleus
inward
Reduce ossicular conduction
Protect cochlea, mask low-frequency sounds
in the env., and dec. sensitivity to own voice
14. Sound energy Mechanical energy
Hydraulic movements Chemical energy
Electrical energy BRAIN
Mechanical Energy: Vibrations of the eardrum
lever-like action of the ossicles
Hydraulic Energy: Faceplate and oval window
Organ of Corti
15.
16. Scala tympani – perilymph
Scala vestibuli – perilymph
Scala media – endolymph
Reissner’s membrane (vestibular membrane) – s.
vestibuli from s. media
Basilar membrane – s. media from s. tympani;
modiolus (high freq. at oval window, low freq. near
the apex)
Organ of Corti – contains a series of
electromechanichally sensitive cells, hair cells;
transduces pressure waves to action potentials
17. Tympanic
membrane>malleus>incus>s
tapes>oval window>scala
vestibuli>scala
tympani>basilar
membrane>hair cells
receptors
Impedance matching-ossicular
system reduce distance but
increase the force of
movement by 1.3X about 22X
pressure exerted in the fluid.
18. The movement of the
basilar membrane
cause the hair cell
stereocilia to bend.
Stereocilia is
directionally sensitive:
Upward towards scala
vestibuli: hair cells
depolarized
Down towards the
scala tympani:hair cell
hyperpolarized
19. From the bending of
the stereocilia opens
ionic channel>influx of
K.
Membrane potential
decreased to -50mV
from 60mV(resting
membrane potential)
Opens the Ca2+
channel
21. 1st order neuron: located in SPIRAL
GANGLION
2nd order neuron: dorsal and ventral cochlear
nuclei[form 3 groups of acoustic striae(lateral
lemniscus): ventral striae-most prominent
forms trapeziod body]
3rd order: superior olives nucleus
4th order neuron: medial geniculate nucleus
22. Area 41 and 42
>>Primary auditory area-
anterior part: low frequency
Posterior part:reception of high frequency
Area 22
>>Secondary auditory area
Interpretation of sound and for association of
auditory inputs.
23. Superior olivary nucleus- fibers joins ipsi and
contralateral lateral lemnisci. Localization of
sound in space
Nucleus of lateral lamniscus- send axons on
both epsi and contralateral lemnisci. Aids in
bilateralism by sending axon to the
contralateral side.
24. Whispered Voice Test
Ticking Watch Test
Weber Test
Rinne Test
Schwabach Test
25.
26.
27.
28.
29.
30.
31.
32.
33. Conductive hearing loss
Neural hearing loss (Nerve deafness)
Mixed hearing loss
35. auditory nerve, which goes from the inner ear
to the brain, fails to carry the sound
information to the brain
cause a loss of loudness or a loss of clarity in
sounds.
Mixed hearing loss
combination of conductive and neural
hearing losses
38. Ear infections
cause fluid or mucus to build up inside the ear
fluids drain out of the ear or are absorbed into the
body
Otosclerosis
common cause of hearing loss
hereditary disease in which portions of the middle
ear or inner ear develop growths like bony
sponges
can be in the middle ear, the inner ear, or both
places
49. allows you to switch from the normal
microphone setting to a "T-coil" setting to
hear better on the telephone.
Direct audio input
allows you to plug in a remote
microphone or an FM assistive
listening system or connect to other
devices
50. helps suppress squeals when a hearing aid
gets too close to the phone or has a loose-
fitting earmold
51. Behind-the-ear (BTE) aids
"Mini" BTE (or "on-the-ear") aids
In-the-ear (ITE) aids
In-the-canal (ITC) aids and completely-in-
the-canal (CIC) aids
52.
53. contained in a small plastic case that rests
behind the ear
case is connected to an earmold or an
earpiece by a piece of clear tubing
often chosen for young children because it
can accommodate various earmold types
can help with all types of hearing loss, from
mild to profound
Sound travels from the earmold into the ear
54. fits behind/on the ear, but is smaller
very thin, almost invisible tube is used to
connect the aid to the ear canal
allow not only reduced occlusion or "plugged
up" sensations in the ear canal
mild hearing loss who can still hear low- and
mid-frequency sounds
55. contained in a shell that fills in the outer part
of the ear
mild to severe hearing loss
it can accommodate directional microphones
and other added features
56. contained in tiny cases that fit partly or
completely into the ear canal
smallest hearing aids available
In-the-canal (ITC) aids
works only for mild to moderate hearing loss
users sometimes experience feedback noise
with this type of hearing aid because the
microphone and receiver sit close together
57. Completely-in-the-canal (CIC)
appropriate for mild to moderate hearing
loss, and it's even smaller than the ITC
hearing aid
barely visible
59. aids amplify sounds
amplify all sounds equally
Digital hearing aids
contain a computer chip
analyzes the sound based on the
person's hearing loss and listening
situation
adjusts for feedback
60. Young, P.A., Young,P.H.,&Tolbert,D. (2008).
Basic clinical neuroscience. (2 nd ed.).
USA:Lippincott Wlliams and Wilkins
Hall, J.E., (2010). Guyton and Hall Textbook of
Medical Physiology. (12th ed.).
Ganong,William F.(2006).Review of Medical
Physiology 23rd edition.San
Francisco,California:Lange Medical
Publications
Triggers presynaptic vesicular vesicle to release the neurotransmitter onto the post synaptic sites at the distal ends of spiral ganglion. This lead to activation of the of afferent nerve.