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