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55 Cards in this Set

  • Front
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Prevalence of hearing loss
3/10 >60 y/o
1/6 41-59 (baby boomers)
1/14 29-40 (generation x)
1.4 million <18 y/o
3/1,000 infants born w/ severe-profound hearing loss
myths
-only affection old people
*65% are <65 y/o
*>6 million 18-44 w/ HL
*1& 1/2 million school age

if i had HL my dr would have told me
only 13% drs routinely screen
SLP skill sets
-conduct screening tests
-interpret audiograms
-troubleshooting of amplification or assistive technology
-assist in the referral and access to audiological services as well as provide basic information
particle motion
energy->vibration->medium->receptor
*need receptor
*vibration and receptor are physiological measure
vibration and particle motion
sound wave propagation is proportional to longitudinal propagation vs. transverse propagation
compression vs. rarefaction
compression: molecule cluster
rarefaction: molecule disperse
transverse vs. longitudinal
transverse: wave in which the motion of the molecules of the medium is perpendicular to the direction of the wave
longitudinal: a wave in which the particles of the medium move along the same axis as the wave
dampening
diminished vibration due to friction
*decreased speed across increase time
2 properties an object needs
1. elasticity: tendency of material to return to original position after disturbance
2. inertia: an object in motion continues in motion
Mediums
air: 344 meters/sec
water: 1497 meters/sec
solid: quick
velocity
*subjective correlate:
speed at which object travels
subjective correlate: pitch
speed/velocity
depends on density of medium
air vs WATER
HUMID vs dry air
fresh vs SALT WATER
velocity formula
velocity(m/s)= displacement(m)/time
Acceleration formula
acceleration(m/s squared)= change in velocity(m/s)/time
periodic vs. aperiodic
periodic: predicted movement, pure tone, simple harmonics, distinct pitch, narrow tuning, limited dampening, sine wave
aperiodic: unpredicted movement, no tone, excessive dampening, broad spectrum
amplitude vs. frequency
amplitude: extent of vibratory movement (direct proportion to displacement)
frequency: # of complete oscillations/time in Hz(direct proportion to velocity)
Sine wave terminology
physiological (objective): psychological (subjective
-frequency(HZ)->pitch
-intensity (dB)-> loudness
-amplitude-> loudness
-phase-> cancellation
wavelength
distance between 2 peaks
frequency=velocity/wavelength
phase
-measured in degrees
-perceptional correlate is cancellation/reinforcement
-360' in one cycle
-"in phase"= reinforcement
"out of phase": at 180' difference=cancellation
complex vibration
combination of 2 or more waves
Periodic: tonal, repeats regularly with time(voice,singing,music)
Aperiodic: atonal, no repetition with time(noise,static)
complex periodic sounds
-component+component=resultant
-resultant depends on phase and amplitude of component
-use reverse fourier analysis
-finding the fundamental frequency(lowest component of resultant) and harmonics
-domain of time vs domain of amplitude
fundamental frequency
shapes resultant in complex waves, frequency remains same in resultant
characteristics of complex waveforms
Upper Band limit
lower band limit
band width
center frequency
filters
high pass
low pass
band pass
band reject
in terms of frequencies allow pass
decibel
unit used to define sound intensity
1. involves ratios
2. utilizes logarithms
3. non-linear
4. expressed by specified reference levels
5. relative unit of measure
intensity
w/cm2 amount of power per area
sound pressure
dynes/cm2 amount of force per area
dBSPL 10^-16 w/cm2
20Xlog (p/pu)=dBSPL
dBIL .0002 dynes/cm2
dBIL=10xlog(1/16)
0dBIL
0dBSPL
softest sound audible to humans
dBHL
determine hearing sensitivity
dB reference levels
0dBHL=normative referenced HL
0dBIL=10^-16 W/cm2
0dBSPL= .0002 dynes/cm2
never means absence of sound
0dBSL= # of decibels above a hearing level(subjective)
peripheral auditory system
-entire ear except the brain
-pinna/auricle
-external auditory meatus
-tympanic membrane
-ossicles
-cochlea
-vestibular system
central auditory system
-brain/neural system
-central function
peripheral auditory system
outer ear-> middle ear->(conduct vibrations to inner ear)-> inner ear(give sense of hearing and carry nerve signal to brain)
Outer ear
Pinna: shape of sounds and localization
External auditory meatus: 1/3 cartilage(outer), 2/3 osseous(inner), epithelium covering contiguous with the tympanic membrane, glands(cerumincus-wax,sebatious-hair,oil)
functions of the outer ear
1. narrow canal and long canal protects from foreign bodies
2. ceruminous, sebacious glands lubricate and protect canals from infection
3. pinna orientation collects sound in front of listener better than sound in back
4. natural resonance increases sounds pressure ~15 dB @~3500 Hz
middle ear ossicles
malleus, incus, stapes
eustacian tube
-provides aeration and drainage of ME
-equalizes pressure on both sides of TM
-adults ~35 mm @ 45 degree angle
-children ~2-mm more horizontal
-upper 1/3 bone
-lower 2/3 cartilage
-isthmus meeting pt
middle ear
tympanic membrane (separates middle and outer ear
ossicles
eustacian tube
tympanic membrane
(ear drum) 3 layers:
-outer/periph layer with epithelial cells from ear canal
-inner/central layer mucous membrane from middle ear
-in b/w layer tough fibrous, connective and radial tissue

-held together by tympanic annulus=pars tensa
-notch of rivinus=pars flaccida
-semitransparent @55' angle create cone of light
-umbo center of membrane; malleus attach
middle ear muscles
stapedius muscle: smallest skeletal muscle in human body(pulls stapes down and back stiffen chain, inervated by CN VII)
tensor tympani: pulls malleus upward, inervated by CN V
functions of middle ear
-regulate pressure change
-carries vibration from air-filled outer ear to fluid filled inner ear
-30 dB loss
-compensates by:
1. area ratio (~25dB)-large area (TM)->smaller area(oval window)
2. curved membrane(~6dB)-vibration involves greater displacement for curved membrane & less displacement for manubrium
3. lever system(~2dB)- malleus constitutes the longer leg of lever and the incus is the shorter leg
otoscopy
exam visualize pinna,external auditory meatus,TM
otoscope: handle, head(light bulb magnifying lens), cone(in ear)
specula: cover
auricle/pinna malformation
anotia: absense of pinna
microtia: pinna small
atresia: lack of canalization
stenoses: narrowing of EAM

-otoplasty used for protruding auricles only
-spacers for mild cases of stenosis
inner ear
sensory organ/cochlea
oval window/round window
3 portions:
1. scala vestibula
2. scala media (organ of corti)
3. scala tympani
helicotrema
spiral limbus
vestibular system
8th nerve
cochlea
outer duct of cochlea is osseus labrynth and covered with band of connective tissue called spiral ligament (3.5 cm and 2.5 turns)

inner duct is membraneous labrynth
inner ear fluids
ENDOLYMPH
exists in scala media
high in potassium ions
colorlesss
tasteless
incompressible

PERILYMPH
exists in scala vestibula/tympani
comparable to CSF
high in sodium
colorless
tasteless
incompressible
organ of corti
in scala media
tectorial membrane
tunnel of corti
outer hair cells (3 rows)
inner hair cells (1 row)
hair cells
OUTER HAIR CELLS (mobile)
cylindrically shaped
~12000
steriocilia at apex embedded into tectorial membrane
mechanical fine tuning due to motility
5% go to brain

INNER HAIR CELLS
flask shaped
~3500
steriocilia at apex NOT embedded into tectorial membrane
stationary
95% go to brain
hair cell transduction
-the displacement of the basilar membrane due to vibration of the perilymph in ST creates the outer hair cell steriocilia to shear against the tectorial membrane
-Excitation: opening of pores causing - ionic flow into the highly + charged endolymph
-Inhibition: shearing in opposite direction closes pores and stops the flow of ions
-the release of neg. ions into the pos. charged endolymph is accepted by the stereocilia of the IHC and gives rise to electrical potentials
-therefore conversion of mechanical energy to electrical energy is induced by shearing motion of the OHC=cochlear michrophonic
-OHC motility allows for an increase in the chemical response which allows inner hair cells to react even with low intensity stimulation
theories of hearing:
Hemholtz vs Rutherford
Hemholtz:
-BM has segments that are HZ tuned due to tension
-Vibrations would move BM and OHC at diff. segments and frequency selectivity
-does not account for dampening due to sharply tuned BM
-does not account for seperation of quick stimuli

Rutherford:
-BM vibrates as whole and HZ selectivity occurs at higher neural stations
-Does not account for frequency specific HL
-does not account for refractory period
Central auditory pathway
cochlea->auditory nerve(some end at ventral and dorsal nucleus)->superior olivary complex(1st decussation, some end)->lateral lemniscus->inferior colliculous-> medial geniculate body->course auditory cortex(sound given meaning)
vestibular system
3 systems of balance:
visual system
proprioception
vestibular
development of the ear
-begins at 3 weeks gestation
-vestibular portion develop earlier than auditory
4 week:pinna
9 week: cochlea turns complete
10-12 week: organ corti begin form
16 week: cochlea adult size
24 week:ossicular chain ossify