Lecture #5 - hearing disorders Flashcards
how many components does the inner ear have ?
3
what are the 3 components of the inner ear ?
- vestibular apparatus
- cochlea
- auditory nerve
what are the 7 main parts of the ear ?
- pinna
- ear canal
- ossicles
- ear drum
- eustrachian tube
- cochlea
- auditory nerve
what is the function of the vestibular apparatus ?
responsible for balance and equilibrium (where our body is in space)
what are the two parts of the vestibular apparatus ?
semicircular canals & vestibule
what does the semicircular canals help sense and maintain ?
balance
what is the vestibule ?
the entry way to the inner ear
how many organs does the vestibule contain ?
two
what are the two organs in the vestibule responsible for ?
linear acceleration and gravity
what part of the ear is the cochlea ?
the inner ear
what is another term for teh “cochlea” ?
organ of hearing
describe the makeup of the cochlea :
- hard-walled
- fluid-filled chamber
- in coiled/shell shape
how many flexible openings that is covered by membrane does the cochlea have ?
2
what are the two openings of the cochela ?
oval window and round window
what does the cochlea do?
takes mechanical energy from the middle ear to electrical impulses
what connects to the oval window of the cochlea ?
the stapes
what is the function of the oval window ?
it receives vibrations from the stapes (middle ear bone) and passes them into the fluid-filled cochlea
what is the function of the round window ?
it helps release pressure by moving in the opposite direction of the oval window
what is the basilar membrane of the inner ear ?
The basilar membrane is in the cochlea and vibrates in response to sound. These vibrations activate hair cells, which send signals to the brain for hearing
describe the structure of the basilar membrane :
- runs the length of the cochlea (base to apex)
- around 36 mm long
what is the cochlea (basilar membrane) covered with ?
cilia (tiny hair cells)
around how many ciliar are there in a healthy human cochlea ?
20,000
how are the cilia’s placed in rows ?
one row of inner and three rows of outer hair cells
what connects to cilia hair cells ?
auditry nerve
what does the basilar membrane detect ?
frequency sounds
TRUE OR FALSE
the basilar membrane runs throughout the cochlea but varies in thickness and
TRUE
how does the cilia work in the basilar membrane ?
they are specialized to detect different sound frequencies in specific areas - high frequencies at the base and low frequencies at the apex. their hair cells are present but their sensitivity varies along the membrane
where in the cochlea do we gather high frequencies ?
at the base
where in the cochlea do we gather low frequencies ?
at the apex
what is the oragan of corti ?
- is the hearing organ inside the cochlea
- It sits on the basilar membrane and contains hair cells that detect sound vibrations
describe the endolymph vs prilymph :
- Endolymph: Found inside the cochlear duct, it has a high concentration of potassium, which helps activate hair cells for hearing.
- Perilymph: Surrounds the cochlear duct and is located in the spaces above and below it. It has more sodium and helps transmit sound vibrations to the basilar membrane.
what happens when these hair cilia cells move ?
they send electrical signals to the brain, allowing us to hear
describe the endolymph :
Found inside the cochlear duct, it has a high concentration of potassium, which helps activate hair cells for hearing.
describe the perilymph :
Surrounds the cochlear duct and is located in the spaces above and below it. It has more sodium and helps transmit sound vibrations to the basilar membrane
where is the endolyph located ?
found inside the cochlear duct
where is the perilymph located ?
surronds the cochlear duct and is located in the spaces above and below
how does fluid move in cochlea ?
fluid moved by motion of stapes at oval window
what happens to the ciliar as fluid moves across the membrane?
cilia are bent
TRUE OR FALSE
stimulates specific place on basilar membrane based on frequency ?
TRUE
what is tonopic organization ?
is how the cochlea and brain organize sound by pitch
what does 1,000-2,000 Hertz represent closests to ?
base
what does 20-1,000 Hertz represent closests to ?
apex
what is the organ of corti ?
end organ of hearing
where do we find the organ of corti ?
sits on top of basilar membrane
what does the organ of corti do ?
converts mechanical sound energy into electrical impulses
what is the auditory (vestibulocochlear) nerve ?
is the nerve that carries sound and balance information from the inner ear to the brain, helping us hear and maintain balance
what is another name for the auditory (vestibulocochlear) nerve ?
VIIth cranial nerve
what is the auditory (vestibulocochlear) nerve part of ?
the peripheral nervous system
where do the 30,000 afferent (sensory ascending) connections come from (for the auditory (vestibulocochlear) nerve :
- inner hair cells
- vestibular system
how many afferent connections does the auditory (vestibulocochlear) nerve contain ?
30,000 afferent (sensory ascending) connections
where does the auditory (vestibulocochlear) nerve terminate ?
at cochlea nucleus in brainstem
what is the central auditory system ?
is the part of the brain that processes sound signals sent from the ear. It helps us understand and interpret sounds, like speech and music.
what is the ascending binaural pathway ?
is the neural pathway that carries sound information from both ears to the brain, allowing us to locate sounds and perceive them in three dimensions.
“right and left ear inputs” and “contralateral and ipsilateral connections” defines what ?
the ascending binaural pathways
what does binaural representation of sound mean ?
our brain uses information from both ears to understand where sounds come from. It compares the timing and loudness of sounds received by each ear, helping us locate the direction and distance of the sound source
how do the directions work transporting information from one ear to the side of brain ?
The left ear primarily connects to the right side of the brain, and the right ear connects to the left side. However, some auditory information from each ear also goes to both sides of the brain, allowing for sound processing and localization.
what are the main parts of the central auditory system ?
- cochlea
- auditory nerve
- cochlea nuclei
- brainstem
- brainstem nuclei
- auditory cortex of brain
give a step-by-step explanation of how sound travels through the central auditory system:
- Cochlea: Sound vibrations are converted into electrical signals.
- Auditory Nerve: Signals travel through the auditory nerve to the brain.
- Cochlear Nuclei: Signals first reach the cochlear nuclei in the brainstem.
- Brainstem: From there, signals are processed in various brainstem areas.
- Brainstem Nuclei: Further processing occurs in specific nuclei within the brainstem.
- Auditory Cortex: Finally, signals reach the auditory cortex in the brain, where we perceive sound.
how does hearing happen ?
- sound waves (we hear things)
- outer ear collects and channels
- middle ear (turns sound into mechanical energy)
- inner ear (gets moved from stapes t inner ear oval, becomes fluid
- travels to auditory nerve (where inerupts signals so we can undestand
- travels to brainstem
- goes to cortex
what are the three T’s of hearing ?
transmission, transformation, transduction
what is “sound” ?
sound is a type of energy created by vibrations that travel through the air as waves. When these waves reach our ears, they are interpreted by our brain, allowing us to hear
how does sound phsyically occur ?
results from a disturbance of air particles
how is sound formed ?
by vibrations
what do vibrations create ?
sound waves
how are sound waves formed ?
- sound source vibrates
- air molecules are “pushed:, causing them to be compressed
- air molecules “rebound”, causing them to spread apart or become decompressed
- repeated compression and decompression creates a waveform
what is a wave form ?
is a visual representation of a sound wave, showing how the sound’s amplitude (loudness) changes over time. It illustrates the shape and pattern of the sound
how are waveforms formed ?
Waveforms are formed when a sound source, like a vibrating object, creates pressure changes in the air
FILL IN THE BLANK
1 sound wave vibration (cycle) per second = __________
1 Hertz
what is considered one sound wave cycle ?
one complete compression and decompression/rarefaction of the air
define frequency :
rate of vibration of sound source
what term is used to describe “the number of complete sound wave cycles in one second” :
frequency
what is the unit of measuremnt for frequency ?
Hertz (Hz)
1000 complete sound wave cycles in one second = how many hertz ?
1000 Hz
between how many Hz can humans hear ?
20 - 20,000
how are low hertz sounds percieved ?
as low pitch
how are high hertz sound percieved ?
as high pitch
less vibrations = higher or lower pitch ?
lower
what does it mean in our ear if we hear a higher frequency ?
vibrates eardrum more rapidly, therefore higher perceived pitch
define “pure tone” :
sound that vibrates at only one frequency
define “complex sound” :
contains more than one frequency and motion pattern is complex but has a pattern
( has a sound wave, is complex, but has indeed a pattern)
define “noise” :
sound that has no consistent vibratory pattern (i.e., random motion) (no specific pattern)
how do you differentiate frequency vs amplitude/intensity ?
frequency = pitch while amplitude/intensity = loudness
what do we measure frequency in ?
hertz
what do we measure amplitude in ?
decibals
define frequency in terms of vibrations :
of vibrations/sound waves per second
define amplitude in terms of vibrations :
amount of energy of a vibration
TRUE OR FALSE
speech = noise
FALSE
what is the difference between speech and noise ?
- Speech: Organized sounds with meaning, like talking or singing, that we use to communicate.
- Noise: Unorganized sounds that don’t have a clear pattern or meaning, like background sounds or static
what is the SIMPLEST and EASIEST way to differentiate between sound and noise ?
sound = organized
noise = unorganized
define amplitude/intensity (loudness) :
- distance or amount of sound wave motion
- height of sound wave = point at which air particles are at maximum disturbance
TRUE OR FALSE
we must have same frequency with same intensity ?
FALSE
same frequency can have different intensity
what is the unit of measurement for amplitude ?
decible (dB)
what is loudness ?
- how it sounds to you
- how amplitude/intensity sounds to listener (perceptual rather than physical/acoustic)
what does it mean for ear if we have higher amplitude ?
hits eardrum with greater intensity and sound is perceived as louder
dedcibel rating higher than what can cause permanent hearing damage ?
80
define “hearing loss” :
condition in which individual is unable to detect or distinguish range of sounds normally available to human ear
define “hearing imapairment” :
Any partial or total inability to hear, affecting communication.
define “hearing disorder” :
A condition that affects normal hearing, often with specific causes or symptoms
define “deafness” :
minimal hearing or complete loss
define “hard of hearing” :
get benefit from hearing aid
define “Deaf” :
member who identifies in the deaf community
define “deaf” :
only talking about hearing loss
define “Deaf community” :
views as community not a disability
when can we see a decrease in hearing activity or clarity due to ?
malfunction of hearing mechanisms
how many classifications of hearing loss are there ?
4
what are the four classifications of hearing loss ?
- type of hearing loss
- degree of hearing loss
- location of hearing loss
- configuration of hearing loss
what are the 3 types of hearing loss ?
- conductive
- sensorineural
- mixed
define conductive hearing loss :
This occurs when sound is blocked from reaching the inner ear, often due to problems in the outer or middle ear, like ear infections or fluid buildup
define sensorineural hearing loss :
This happens when there is damage to the inner ear or the auditory nerve, often caused by aging, noise exposure, or illness
define mixed hearing loss :
This is a combination of both conductive and sensorineural hearing loss, meaning there are issues in both the outer/middle ear and the inner ear or auditory nerve
the following defines what type of hearing loss ?
- problems affecting sound transmission through outer or middle ear
- flow of sound to the middle and inner ear is disrupted
- reduced loudness of sound
- difficulty detetcting faint sound
conductive hearing loss
what type of hearing loss is “problem conducting sound from outer ear to inside” ?
conductive hearing loss
what is a perforated tympanic membrane (eardrum) ?
hole in eardrum and it bursts
the following defines what type of hearing loss ?
- due to damage to inner ear or auditoru nerve
- affects loudness and clarity of hearing
- permanent loss
sensorineural hearing loss
which type of hearing loss is experienced by 90% of people? is the most common ?
sensorineural haering loss
the following defines what type of hearing loss ?
- combined conductive and sensorineural hearing loss
- both middle and inner ear affected
- SNHL permanent, conductive HL may be addressed
mixed hearing loss
in mixed hearing loss which part is more prominent ?
senosrineural
the more profound the degree of hearing loss = _________ for the ability to hear speech
unable to clearly understanf even amplified speech
the more mild the degree of hearing loss = _________ for the ability to hear speech
difficulty hearingt soft speech and conversations, but can manage in quiet environemnts
what are the degrees of hearing loss ?
- none
- mild
- moderate
- moderate-to-severe
- severe
- profound
can you describe “mild” degree of severity of hearing loss :
Difficulty hearing soft sounds and understanding speech in noisy environments
can you describe “moderate” degree of severity of hearing loss :
Trouble hearing regular conversation without hearing aids
can you describe “severe” degree of severity of hearing loss :
Very limited ability to hear speech, even with amplification
can you describe “profound” degree of severity of hearing loss :
Cannot hear most sounds, may rely on sign language or other communication methods.
what are the location/causes of hearing loss ?
- disorders of outer ear
- disorders of middle ear
- disorders of inner ear
- disorders of central auditory system
what are the degree/severity of hearing loss dependent on ?
based on the quietest sound a person can hear, measured in decibels (dB)
describe outer ear disorders :
problems like earwax buildup, infections, or blockages that affect sound entering the ear
describe middle ear disorders :
issues like ear infections, fluid, or damage to the ear bones that block sound from reaching the inner ear
describe inner ear disorders :
damage to the cochlea or hair cells causing hearing loss, often from aging, loud noise, or infections.
describe central auditory system disorders :
problems with how the brain processes sound, even when the ears work fine, affecting understanding of speech and sound location
what are some disorders of the outer ear ?
- atresia
- ear canal obstruction
- ottis externa
what is atresia ?
absence of normal opening
what is ear canal obstruction ?
something in ear (ex. earwax) blocking the path of the ear canal
what is ottis external ?
infection of ear
what is the treatment for atresia ?
surgery to create an ear canal
what is the treatment for ear canal obstruction ?
remove blockage (like earwax) using drops or professional cleaning
what is the treatment for ottis externa ?
Use ear drops (antibiotics or antifungals) to reduce infection and inflammation
what are disorders of the middle ear ?
- perforated ear drum
- ottis media
- otoclerosis
what is a perforated ear drum ?
hole in eardrum
what is conductive hearing loss ?
means sound can’t travel efficiently through the outer or middle ear, often due to blockages or damage. This makes it harder to hear quiet sounds
what is the treatment for perforated ear drum ?
can heal on own in couple months or weeks
what is another term for eardrum ?
tympanic membrane
what are the three classifications of the otitis media ?
acute, subactute and chronic
what is an acute classification of the otitis media ?
less than 3 weeks
what is an subacute classification of the otitis media ?
3 weels to 3 months
what is a chronic classification of the otitis media ?
longterm… need help from tube
what is otitis media ?
is an infection or inflammation of the middle ear, often causing pain and fluid buildup behind the eardrum
why are kids more likely (2/3 by the age of 2 years old) than adults to experience otitis media ?
due to the angle of the eustachian tube
what is otosclerosis ?
abnormal spongy bone growth that grows instead of normal bone that prevents proper movement of stapes at oval window
TRUE OR FALSE
otosclerosis is NOT hereditary, its due to diets and lifestyle
FALSE
otoscleosis is often hereditary
what cause otosclerosis ?
we don’t know
how can we cure ostosclerosis ?
stapedectomy
if we are experiencing disorders of the inner ear what type of hearing loss are we experiencing ?
sensorineural hearing loss
what are the 7 causes/locations of disorders of the inner ear ?
- genetics and heredity
- pre-perinatal
- infections
- ototoxic medications
- noise exposure
- presbycusis
- meniere disease
what are some examples of genetic and heredity disorders of the inner ear ?
- autosomal dominant
- autosomal recessive
what are some examples of pre-perinatal disorders of the inner ear ?
- maternal rubella
- CMV
- anoxia
- low birth weight/prematurity
- cytmegalovirus
what are some examples of infection disorders of the inner ear ?
- meningitis
what are some examples of ototoxic medications disorders of the inner ear ?
- certain antibiotics
- chemotherapy drugs
- high dosages of aspirin
what are the most common types of hearing loss ?
disorders of the inner ear
what are ototoxic medications ?
drugs that can damage the inner ear, leading to hearing loss, balance issues, or ringing in the ears
what does autosomal dominant vs recessive mean ?
Dominant: A genetic condition where only one copy of the faulty gene (from one parent) is enough to cause the condition.
Recessive: A genetic condition where both copies of the gene (one from each parent) must be faulty for the condition to occur.
describe noise exposure related hearing loss of the inner ear :
- noise-induced hearing loss
- impact influenced by intensity/duration of noise, exposure, hearing protection, recovery time between exposures, redisposition, and other cochlear damage
what type of frequency is noise exposure damage ?
high frequency hearing loss
if noise exposure disoreders of the inner ear mean high frequency hearing loss, what may we have difficulty percieving ?
difficulty percieving those high frequencies
what is the recovery time for a noise exposure related inner ear disorder ?
it can very - depends on the severity of the damage … temporary = hours to a few days while permanent damage = recovery isn’t possible, though hearing aids or therapies can help manage symptoms
what is presbycusis ?
degeneration of inner ear and other auditory structures due to normal aging process
(deterioration over time with hearing)
what type of frequency hearing loss is presbycusis ?
high frequeuncy hearing loss
what is the common factor to cause presbycusis ?
age related (as you get older)
what are the common ages to experience presbycusis ?
35% of ages 65-75 and 50% of ages 75+
how to treat presbycusis ?
can’t be cured, but it can be managed with:
- Hearing aids to improve hearing
- Assistive listening devices for specific situations
- Communication strategies like lip reading or using apps
- cochlear implants may be recommended
what is meniere disease ?
increased pressure in inner ear, of unknown cause
what does meniere disease lead to ?
hearing loss, vertigo, tinnitus, pressure/pain
what is the treatment to meniere disease ?
surgery to elevate symptoms or we can use steroids
disorders of the central auditory system is also known as …
retrocochlear pathology (damage in the area from behind the cochlea)
what part of the body do we see disorders of the central auditory system ?
behind the cochlea (the auditory nerve to the brain)
what is the most common disorder of central auditory system ?
acoustic neuroma
what is “acoustic neuroma”?
benign tumor on auditory nerve (cranial nerve VIIth)
at what age range may we see acoustic neuroma ?
between ages 30-50 (gets worse over time)
in how many ears does acoustic neuroma occur ?
happens in one ear
what are some symptoms accompanied by acoustic neuroma ?
ringing, vommiting and dizziness
what are some symtoms of vertigo ?
- a spinning or dizzy sensation
- loss of balance
- nausea or vomiting
- sweating
- feeling lightheaded or unsteady
- trouble focusing the eyes
how many configurations of hearing loss are there ?
4
what are the 4 configurations of hearing loss ?
- high-frequency hearing loss
- flat hearing loss
- unilateral vs. bilateral hearing loss
- symmetric vs. asymmetric hearing loss
TRUE OR FALSE
you can only have one configuration of hearing loss at a time ?
FALSE
you could have across all frequencies or only at certain frequency sounds
define. high-frequency hearing loss :
Difficulty hearing high-pitched sounds, like birds chirping or certain speech sounds
define flat hearing loss :
Hearing is reduced equally across all sound frequencies, making everything quieter
define unilateral vs. bilateral hearing loss :
- Unilateral: Hearing loss in one ear
- Bilateral: Hearing loss in both ears
define symmetric vs. asymmetric hearing loss :
- Symmetric: Hearing loss is the same in both ears
- Asymmetric: Hearing loss is different in each ear
what is “tinnitus” ?
- another type of hearing loss
- continuous noise in ears
- ringing
what is “auditory processing disorder” ?
- is a condition where the brain has difficulty understanding and processing sounds, even though hearing is normal. People with APD may struggle to follow conversations, especially in noisy places, because their brain doesn’t process sound in the usual way.
- normal peripheral hearing but imapired processing, or interpretation, of auditory messages
in auditory processing disorders, what problems might occur in one or more aspects of?
- sound localization
- auditory discrimination
- recognition of sound patterns
- auditory performance
what might we use to assess hearing disorders ?
audiometry
what is an “audiometry” ?
- a quantitative measurement of hearing
what type of testing is “audiometry” ?
behavioural and physiological testing
what are the 3 main audiometry tests ?
- pure-tone audiometry
- immittance testing
- electrophysiologic testing
define #1. pure tone audiometry :
- behavioural measurement of hearing threshold using audiometer
- tests loudness thresholds in response to pure tones at different frequencies
- 250Hz-8000Hz
- threshold dB
which type of test “tests the loudness you can perieve and process conversatinal speech” ?
pure-tone audiometry
what is the most common out of the three tests of assessment ?
pure tone audiometry
what are the two types of pure-tone testing ?
air conduction and bone conduction
define air conduction :
earphones test entire peripheral system
define bone conduction :
bone vibrator on skull tests inner ear functioning only
which of the two types of pure-tone testing bypasses the outer and inner ear ?
bone conduction
which of the two types of pure-tone testings do we conduct first ?
air conduction
when do we use bone conduction ?
when we assume its an inner ear ossie because were skipping the outer and middle ear
in regards to responses charted on audiogram what colour is left ear and which is right ear ?
BLUE X = left air conduction
RED O = for l=right air conduction
< and > = for left and right bone conduction
what is immittance testing ?
measure how easily sound travels from air to bone and gives information about mobility
what are the 2 types of immittance testing ?
tympanometry and acoustic reflex
what is tympanometry ?
- test of tympanic membrane mobility
- visualizes the relationship between air pressure in the ear canal and movement of the ear drum and ossicular chain
FILL IN THE BLANK
conducted using tympanometer generated tympanogram which plots ________ _______
eardrum compliance
what are the 3 types we may see on tympanograms ?
TYPE A = normal
TYPE B = flat
TYPE C = off-centre
define TYPE A = normal tympanogram :
normal midle ear function
define TYPE B = flat tympanogram :
suggestive of middle ear fluid or punctured eardrum
define TYPE C = off-center tympanogram :
suggestive of eustacia tube malfunction
what is acoustic reflex testing ?
- involuntary contraction of stapedius muscle in middle ear
- protextive reflex to prevent extremely loud sounds from damaging cochlea
how does acoustic reflex testing work ?
- response to loud sound tested using probe, often same device as used for tympanometry
- absence of response can suggest middle ear problem, severe SNL, or brainstem disorder
if we experince no response during acoustic reflex testing, what might this suggest ?
an issue in the middle ear
what is electrophysiologic testing ?
- no bheavioural response required
- for hard-to-test people
- to identify auditory lesion site
what are the two types of electrophysiologic testing ?
- otoacoustic emissions
- auditory brainstem response
what is the main goal of the electrophysiologic test ?
to identify whether there is a problem in the auditory path
describe “otoacoustic emissions” testing :
checks how well the inner ear (cochlea) works by measuring sound waves produced by the ear in response to a sound. It’s often used to screen hearing in newborns and young children
describe “auditory brainstem response” :
is a test that measures how the brain responds to sounds. Electrodes are placed on the head to track the brain’s electrical activity, helping diagnose hearing issues and nerve function.
