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114 Cards in this Set

  • Front
  • Back
What is sound?
A mechanical disturbance propagated through an elastic medium
Mechanical disturbance
displacing one object to another (D,T,K)
Elastic medium
tends to want to maintain it's shape
Frequency
number of cycles per second
diffraction
sound deflects or bends around
small wavelength...
reflects off objects
large wavelength...
bends around objects
Interference
two or more sounds add together
Constructive interference
reinforce one another and add together
Destructive interference
two forces headed in opposite direction and sound is reduced
Modes
Natural frequencies at which objects oscillate. unique to each object
superposition
sum of oscillations. All complex sounds are a superposition ofoscillations
diffraction
bending of sounds around objects
reflection
bouncing of sound off of objects
How do we make sense of our surroundings from sound?
frequency analysis
Outer ear
pinna, ear canal
Middle ear
tympanic membrane, oval window, ossciles
Inner ear
cochlea
Pinna
Sound localization, Directionally-dependent filter
Concha, Ear canal
Funnels sound to amplify important speech frequencies
Tympanic Membrane
Eardrum, contact airborne sound
Ossicular Chain
Impedence match between air and cochlear fluid. Prevents sound from bouncing back out the ear
Oval window
stapes contact with base of cochlea
Middle ear muscles
prevents damage from the inner ear. Acoustic Reflex
Impedance Match
Area differential between tympanic membrane and oval window focuses pressure on oval window. Prevents sound from bouncing back out the ear.
Basilar membrane
Resonant element of inner ear, place code
Organ of corti
hair cells and supporting structures
Tectorial membrane
creates shearing force across stereocillia of hair cells
Hair cells, Sterecillia
electroacoustic transduction
Transduction
conversion of mechanical disturbance in fluids of cochlea to change in electrical potential across hair cell body
Tiplinks/Stereocillia allow...
electrical disturbance to flow
Soma, Axon, Dendrites
Basic structures of all nerve fibers
Myelination
Fatty sheath of axon, electrical insulation
efferent fibers
carry info from brain to ear
afferent fibers
carry info from ear to brain
synapse
connection between nerve fibers
neurotransmitter
chemical substance released by nerve fibers that creates a graded electrical potential
Percentage of afferent nerve fibers connected to the outer hair cells
5%
Percentage of afferent nerve fibers connected to the inner hair cells
95%
Percentage of efferent nerve fibers are connected to the outer hair cells
80%
Percentage of efferent nerve fibers that are connected to the inner hair cells
20%
Specificity
Many to one arrangement (Nerve fibers to Inner hair cells)(Detection)
Sensitivity
One to many arrangement (Afferent nerve fibers to Outer hair cells)(Identification)
Auditory Nerve Complex
Tonotopic Organization, Mapping of frequency to place along the basilar membrane preserved in central auditory nervous system
Cochlear Nucleus
Lateral inhibition, ehances contrast
Superior Olivary Complex
An auditory delay line which helps explain whether sound comes form left or right by localization through coincidence detection
Plasticity
When hair cells no longer synapse at a certain frequency reorganize very rapidly with other hair cells to allow to hear certain frequencies
Definition Threshold
No such thing as all or none threshold. 75% signal strength required for correct performance
Absolute Threshold
Threshold for the signal in quiet. Best sensitivity (1.0 - 4.0khz) of pure tone. Consonants help distinguish the difference between each word
Differential Threshold of Intensity
A little more or less than 1dB
Inferior Colliculus and Medial Geniculate Body
neural networks designed to detect specific features of sound. Specialization for speech
Differential Threshold for Frequency
a fraction of a percent change between 600-2000 Hz. Ex. 1000hz to 1002hz
Differential threshold for phase
Effects of phase only audible through interference. Can either create sound or cancel sound.
Fletcher's Bandlimiting Experiment
Only energy within a critical band of frequencies surrounding the signal are effective in masking the signal
Critical band
250 noise bandwidth - point of which there is no further masking
Duplex Theory; Interaural Time difference
For wavelengths greater than the diameter of the head (f<2000hz),the primary cue is ITD. which ever ear it reaches first
Duplex Theory; Interaural Intensity difference
For wavelengths < than the diameter of the head (f>2000hz), the primary cue is IID. Sound reflects and sound shadow is produced.
Minimal Audible Angle
Threshold change in angle for a change in sound source position (1degree)
"Auditory blind spot"
2000Hz
Echos and the precedence effect
first arriving wavefront dominates perceived location (auditory illusion)
Binaural masking level difference
Improved audibility in dichotic listening. Loud party
Acoustic Trauma
Exposure to intense sound or to moderately intense sounds over long periods of time
Presbyacusis
Hearing loss due to the aging process
Percentage of sensorineural hearing loss due to damage to the stereocillia or hair cells
90%
Sensorineural hearing loss
shearing force subjects delicate stereocillia to potential damage
Threshold elevation at high frequencies
Higher hz have much higher threshold to hear. First thing that goes are high frequencies
Loudness recruitment
don't hear small wavelenghts, loss of OHC's results in abnormal growth of loudness
Frequency Selectivity
loss of OHC's results in loss of frequency selectivity. frequencies become blurred together
Rate of births of newborns with hearing loss
1 in 22 births
Hearing screening
purpose is to identify those who may have a hearing loss
Hearing evaluation
Purpose is to determine degree, shape, type, and possible site of hearing loss; also to determine possible cause and treatment
Conductive hearing loss
problem in outer or middle ear
Sensorineural hearing loss
problem in cochlea, auditory nerve or central auditory nervous system
Mixed hearing loss
both conductive and sensorineural
case history
from client reports and medical records
otoscopic evaluation
check for outer each occlusion
tympanogram
a measure of eardrum and middle ear function
audiogram
pure tone thresholds, air and bone conduction
word recognition score
ability to understand speech at intensity levels well above the threshold of hearing
Air bone gap
Conductive hearing loss, other and middle ear
No air-bone gap
sensorineural hearing loss inner ear and cochlea
Graphs: Shape is linear. What type of hearing loss?
conductive
Graphs: Shape is sloped/curvy. What type of hearing loss?
sensorineural
Otitis Media
infection of the middle ear, most common cause of conductive hearing loss in childeren (conductive)
Otosclerosis
fixation of the stapes, most common cause of conductive hearing loss in adults
Meniere's disease
abnormal volume of fluid within the inner ear (sensorineural)
Presbycusis
hearing loss due to aging, most common overall (sensorineural)
Otoacoustic Emissions
Low level acoustic signals of cochlear origin that may be recorded in the closed ear canal. Hearing screening in newborns
Source of Otoacoustic Emissions
rocking motion of OHC's causes basilar membrane to vibrate, produces sound that travels out the ear canal. Hair cells functioning properly
Auditory Brainstem Response
The ABR is a waveform that is formed by the synchronous electric activity of neurons in various parts of the auditory brainstem. They are typically elicited by acoustic signals that trigger a neural response, but they do not imply hearing. People who don't have behavioral responses
Auditory Brainstem Response: Hearing Loss
Abnormal amplitude and latency indication of hearing loss
Auditory Brainstem Response: Acoustic Neuroma
Tumor on Auditory Nerve
Auditory Neuropathy
a hearing disorder in which sound enters the inner ear
normally but the transmission of signals from the inner ear
to the brain is impaired (Physiological).
Central Auditory Processing disorder
an inability to differentiate, recognize, or understand
sounds when hearing and intelligence are normal
(Psychological).
Sudden Sensorineural Hearing Loss
A rapid loss of hearing occurring over a period of 3 days or less.
List hearing instruments in chronological order
Hearing trumpets, early electronic hearing aids, transistorized hearing aids, Digital hearing aid, in ear hearing aids
How hearing aids work
microphone to circuit to reciever to ear canal and powered by battery
Middle ear plants
Transducer vibrates ossicular chain
Cochlear implants
150,000 people worldwide. Coded signals to transducer which vibrates sclap to electrodes to auditory nerve to brain
Bilateral Cochlear Implants
attempt to provide spatial info
brainstem
electrode stimulation of auditory brainstem
bone conduction
acoustic stimulation of cochlear through bone conduction
cochlear hypoplasia
incomplete development of the cochlea
middle ear cholesteatoma
abnormal skin growth (tumor) in middle ear
ossicular discontinuity
detached bones of the ossicular chain
microtia
(small ear) congenital deformity of the pinna
anotia
(no ear) absence of the pinna
atresia
absence of the ear canal
acoustic neuroma
tumor on auditory nerve complex
Auditory development: birth
startle response to loud sounds, increase sucking in response to sound
5 months
turns head in search of sound, reaches with hands
1-2 years
mobile, doesnt sit still
3-5 years
talks and understand simple intstructions, plays games/computers, likes to please adults
Visual reinforcement response
conditioned head turn response