reducing the negative impact of hearing loss. Mainly in private practice.

Ex. hearing aid fittings and communication strategies

identifying and managing hearing loss in young children. Minimize the impact of HL on speech and language development.

Ex. testing, counseling, setting up rehab activities

Minimizing the impact of HL at school

Ex. hearing screenings, evaultions of children with HL, classroom acoustics, prevention programs

Preventing hearing loss in the workplace by identifying noise cources and measure noise levels.

Ex. Education, using hearing protection devices, reduce noise levels

Tympanic Membrain (eardrum)

Tympanic Cavity (in the petrous portion of the temporal bone)

Epitympanic recess - contains the head of malleus and most of incus

Ossciles - mallues, incus, and stapes

Tensor Tympani

Stapeidal muscle

Eustachian Tube (Auditory tube)

Osseous Labyrinth (in the petrous portion of the temporal bone) - vestibule, semicircular canals, cochlea

Membranous Labyrinth (suspended in the osseous labyrinth) - scalia vestibuli, scalia media, scalia tympani

captures sound

made of fibrocartilage

covered by skin

attached to the temporal bone by extrinsic muscles and ligamnets

oval, S-shaped tube

2.3-3.5cm

lateral 1/3 is cartilage

medial 2/3 is osseous with cilia and glands

has cerumen (ear wax)

very thin

resilient

vibrates in response to acoustic energy

1cm diameter, roughly circular

annulus - thickened, outer ring

cone of light

umbo - central depression

outer, middle and inner layers

located in the petrous portion of the temporal bone

contains the epitympanic recess (head of mallues and most of the incus)

contains the ossicles (malleus, incus and stapes)

the roof, a thin plate of bone that separates the tympanic cavity from the cranium

superior wall

inferior wall

the floor, a thin bone that separates the tympanic cavity from the internal jugular vein

the tympanic nerve runs through the floor

lateral wall

the tympanic membrane

medial wall

oval window and round window

anterior wall

separate the tympanic cavity from the carotid artery

posterior wall

near the Mastoid bone of the skull

Mallues, Incus, Stapes

within the tympanic cavity

transmits acoustic vibration from the TM to the inner ear

the Hammer

largest of the ossicles

most lateral

0.9cm long

anterior ligament is attached with 2 other ligaments

manubrium is the handle and is attached to the tympanic membrane

the anvil

atriculates laterally with the malleus

articulates medially with the stapes

suspened by the posterior ligament

the stirrup

smallest bone in the body

footplate is attached to the oval window

tendon of stapedial muscle is attached to the neck

located above and along the Eustachian tube

attahced to the Manubirum of the Malleus

Innervated by the branch of the mandibular nerve of the trigeminal nerve

Stapedius

smallest striated muscle in the body

tendon inserts on the neck of the stapes

innervated by the stapedial branch of the facial nerve

contraction of the muscles increases he stiffness of the ossicular chain

may provide some sound protection against the low or intense ferequencies

3.5-3.8cm long

extends downward and medially

lateral portion is osseous

medial portion is cartilaginous

normally closed

can open to regulate pressure of the middle ear compared to the outer ear

drains the middle ear cavity

opens during swallowing and yawning by the tensor veli palatini

What is transduction?

It is the process of transforming one form of energy into another form of energy

acoustic > mechanical > electrical

outer > middle > inner

Tympanic Membrain (large) -> Oval Window (small)

Manubrium (TM) to the Stapes footplate (OW)

17:1

20Log(17) = 25dB

25dB gain

Ossicular chain - the length of the manubrium and head of the malleus are longer than the long process of the incus

1.3 to 1

20Log(1.3) = 2dB

2dB of gain

2 to 1

20Log(2) = 6dB

6dB gain

in the petrous portion of the temporal bone

contains the vestibule, semicircular canals, and cochlea

osseous

most lateral portion

superior, posterior and lateral canals

involved in balance and orientation

osseous

sits between the cochlea and the semicircular canals

osseous

medial most portion

3.5cm long

2 and 3/4 rotation

oval window is the entrance

coiled aroudn the central core of the modiolus

round window provides a point of expansion for fluid movements within the cochlea

suspended within the osseous labyrinthe

contains the membranous cochlear labyrinthe

spiral-shaped

contains 3 canals: the scala vestibuli, scala media, scala tympani

on top

the Reisnners Membrane is below it

contains perilymph

formed by the Reissners Membrane above and the Basilar mebrane below

contains endolymph

AKA the chochlear duct

contains the Organ of Corti

contains perilymph

the Basilar Membrane is on top

divides the scala vestibuli from the scala media

extends from the ossseous spiral lamina to the outer bony wall

joins the Basilar membrane at the helicotrema at the apex of the cochlea

the traveling wave

it divides the scala media from the scala tympani

formed at the osseous spiral lamina and extends out to the outer bony wall via the spiral ligament

becomes wider from the base to the apex (more flexible at the apex)

Organ of Corti sits on top 

frequency analyzer

where mechanical energy is transduced into electrical energy

Inner Hair Cells (IHC) - one row, 3500

Outer Hair Cells (OHC) -3 rows, 12,000

Tectorial membrane - gelatinous and extends over the HC

Supporting cells - hold the HC in place

from Cochlea to CNS

30,000 neurons that innervate the cochlea

part of the auditory nerve(VIII)

neural fibers branch off the HC and travel to the spiral ganglion in the modiolus

long neural proceses from the cell bodies in the spiral ganglion travel to the cochlear nucleus

afferent fiber

represent 90-95% all afferent fibers

innervate HC exclusively

only IHC

afferent fibers

synapse on multiple OHC

OHC only

one-to-many innervation

Auditory cortex in the temporal lobe

^

Medial geniculate body (Thalamus)

^

Inferior Colliculus (Midbrain)

^

Lateral Leminscus (Pons)

^

Superior Olivary Complex (Medulla)

^

Cochlear Nucleus

^

Vestibulocochlear Nerve

^

Afferent Fibers (Inner and Outer Radial)

^

Cochlea (IHC, OHC in Organ of Corti)

when molecules are disturbed/vibrated

any object has the potential to produce sound

how long it takes for one cycle to be completed

T = 1/frequency

how many cycles are completed in one second

Hz

F = 1/period

two or more frequencies

pure tones rarely are found in nature

lowest frequency is the fundamental frequency (F0)

each person has their own F0

the distance an object moves from one point of rest (displacement)

if more force is applied then the object will move farther

the more they move, the greater the amplitude

when vibrating objects movethey place a certain amount of forece on adjacent air molecules

the greater the force, the greater the displacement

a push or a pull

dyne (d)

the amount of force over a certain area Ex. TM

micropascals

when any mass is moved, work is done as energy is expended

the capacity to exert physical force

the rate at which energy is expended

watt

the amount of force per unit of area

use Log to represent the ratio between the test (absolute) pressure (X) (Po) and the reference pressure (Y) (Pr)

dB (SPL) = 20 X log (Po/Pr)

Pr  = 20 micropascals

dB

suprathreshold - threshold

60 - 20 = 40 SL