Hearing

What sound wave characteristic determines the volume of the sound

amplitude

lesions central to the cochlear nucleus cause

bilateral hearing loss

The ability of the ear to discriminate sound intensities over an extremely wide range is called _________. a. Vestibulo-ocular reflex b. The "Place" Principle c.The Power Law d. Impedance Matching

c. The Power Law

If a person has selective hearing loss to particular frequencies of sound waves, what is most likely affected?

cochlea and cochlear nerve

Where do 2nd order neurons terminate

cross over in trapezoid body of medulla

What structure converts sound waves to vibrational frequencies for hearing? a. Semicircular ducts b. Utricle c. Rhodopsin d. Tympanic membrane

d. Tympanic membrane

A majority of fibers for the auditory pathway decussate (cross over) in the _______ a. Auditory cortex b. Pons c. Midbrain d. Thalamus e. Medulla

e. Medulla

What do the top of the hair cells sit in

endolymph

What is the difference between endolymph and perilymph

endolymph= high K+ and low Na+2 perilymph= high Na+2 and low K+

symptoms of conductive hearing loss

equal hearing loss in ALL frequencies well preserved speech discrimmination hear speech in noisy background better than in quiet background speak louder and loud speech is heard

What are the 3 components of the ear

external ear, middle ear, inner ear

Where along the basilar membrane will higher frequency sounds stimulate an action potential? Where are lower frequency sounds "heard"

higher frequency= near base lower frequency= near apex

What structures are affected with sensorineural hearing loss

inner ear basilar membrane/cochlea

Where are intermediate frequencies activating the membrane

intermediate distances between the 2 extremes

causes of conductive hearing loss

lesions of external or middle ear impacted cerumen in external canal chronic otitis

which frequencies are mostly affected by attenuation

low frequency

At what volume can low and high frequencies be detected

low=high volume high= low volume

What is the order of the ossicles from external to internal

malleus, incus, stapes

What is a decibel? How does this relate to the "power law"

measurement of loudness power law= ear can discriminate differences in sound intensity ears can barely detect 1 decibel as a change in sound, can tell difference at greater change

Where are low frequency sounds cause activation of the basilar membrane?

near the apex of the cochlea

Where do higher frequency sounds cause activation of the basilar membrane?

near the base of the cochlea

Is endolymph or perilymph more like CSF

perilymph

what do the base of the hair cells sits in

perilymph

what 2 environments will utilize attenuation of sound

protect the cochlea from damaging vibrations and masks low frequency sounds in loud environments

what is "impedance matching"

reduces the distance between the ossicles but increases the force of movement vibration on tympanic membrane is proportional to vibration on stapes

Which tube has endolymph

scala media

Which inner tubes of the cochlea are filled with perilymph?

scala vestibuli and scala tympani

The cochlea: What are the 3 inner tubes of the cochlea?

scala vestibuli, scala media, scala tympani

amplification to the speech specifically goes with

sensorineural hearing loss

symptoms of sensorineural hearing loss

some frequencies (typically low) heard better difficulty hearing speech, especially when mixed with background noise annoyed by loud speech

What 3 characteristics of sounds are detected in the cerebral cortex

sound frequency (pitch) discrimination of sound patterns (speech) determination of direction from which sound came

what 2 muscles are involved in attenuation of sound

stapedius muscle and tensor tympani

Where is the organ of Corti?

surface of membrane in cochlea

How does change in perilymph pressure travel through the cochlea

through the hair cells

peripheral lesions to the cochlear nucleus cause

unilateral hearing loss

What membranes separate each tube of the cochlea?

vestibular membrane (reissner's membrane) separates vestibuli and media basilar membrane separates tympani and media

Is it common to have vestibular symptoms, such as vertigo, with hearing loss

yes

What other pathways will auditory information travel? What purposes are these alternate pathways

-some will traveling to Reticular activating system to respond to loud sounds to wake up; sympathetic NS response -go to vermis of cerebellum=sympathetic NS in response to loud sound

what is the frequency for understanding speech

500-4000Hz

What type of nerves are cochlear nerve? Where do the cell bodies reside?

Bipolar (some references say Pseudounipolar because of the long central processes) and reside in Spiral Ganglion

What type of deafness occurs with absence or disorders of the ossicles? How is it usually managed?

Conduction deafness. Amplification of all frequencies

Unilateral (uniaural, or monoaural) hearing loss indicates the lesion is _______.

Distal to the cochlear nucleus

Which is FALSE concerning attenuation of sound? Masks low frequency sounds in loud environments Slight contraction of the tensor tympani muscle pulls handle of Malleus in Contraction of the stapedius muscle pulls stapes off the oval window Rapidly reduces higher frequency vibrations by 30-40 decibels Protects the cochlear hair cells from damaging vibrations

Protects the cochlear hair cells from damaging vibrations

From the hair cells of the organ of Corti, where do neural impulses travel? Which hair cells stimulate nerve impulses

They go to the spiral ganglion of Corti, which sends axons to the cochlear nerve; inner and outer hair cells

Where do 1 st order nerve fibers from the spiral ganglion synapse?

In the brainstem, cochlear nuclei

What is the organ of corti function

sensory receptor for hearing

How does the brain determine the direction of sound

the time lag between the entry of sound into one ear and its entry into the opposite ear detected in the medial superior olivary nucleus difference between the intensities of sounds in the 2 ears detected by the lateral SON

What are the structures sound waves pass through as they travel to the inner ear

cochlea and semicircular canals, saccule, and utricle

What are the 3 main categories of hearing loss

conductive, central hearing disorders, sensorineural hearing loss

causes of sensorineural hearing loss

congenital/hereditary cochlear damage ototoxic drugs Meniere's disease presbycusis noise induced acoustic neuroma

What is resonant frequency?

the natural frequency of an object

What characteristic of sound is detected by the place principle?

frequency

What sound wave characteristic determines the pitch or tone of the sound

frequency

How is intensity of sound (loudness) detected and relayed

hair cells excite the nerve endings at a more rapid rate= temporal summation hair cells on fringes are stimulated= spatial summation outer layer of hair cells only stimulated when vibration is high, signaling "very loud" to the CNS

How does endolymph differ from perilymph? (Which is TRUE) Endolymph is more electronegative than perilymph due to lower K+ Endolymph fills the scala vestibule and scala tympani Endolymph resembles cerebrospinal fluid The top of the hair cells of the cochlea are in perilymph The -150mV intracellular potential in the hair cell makes it more sensitive to sound vibrations

The -150mV intracellular potential in the hair cell makes it more sensitive to sound vibrations

Contraction of the stapedius and tensor tympani muscles to protect the cochlea from damaging vibrations is _____ Question options: The "Place" Principle The Attenuation Reflex Vestibulo-ocular reflex Impedance Matching

The Attenuation Reflex

What does the stapes contact

oval window

What mechanisms help the brain determine the direction from which a sound comes from? (choose all that apply) Question options: Stimulation of outer layer of hair cells. Hair cells excited at more rapid rate, causing temporal summation. The amplitude of the vibration of the basilar membrane. Hair cells on the fringes of the frequency range stimulated, causing spatial summation. High frequency causes maximal activation of basilar membrane near the apex of the cochlea. The difference between the sound intensities in the 2 ears with the closer ear hearing a noise louder. Time lag between entry of sound into one ear and its entry into the other ear. High frequency sounds activate the basilar membrane near the base of the cochlea.

-The difference between the sound intensities in the 2 ears with the closer ear hearing a noise louder. -Time lag between entry of sound into one ear and its entry into the other ear.

Place in order the sequence of nerve depolarization of the auditory pathway. ___Auditory cortex of the temporal lobe _Dorsal or Ventral cochlear nuclei of the medulla __Medial Geniculate nucleus _Spiral ganglia_ _Superior Olivary nucleus __Inferior colliculus

1. Spiral ganglia 2. dorsal or ventral cochlear nuclei of medulla 3. superior olivary nucleus 4. inferior colliculus 5. medial geniculate 6. auditory cortex of temporal lobe

Place in order the structures that sound waves pass through as vibrations to stimulate the cochlear nerve. __Malleus __Stapes __Oval window __Incus __Membranous labyrinth of cochlea __Tympanic membrane

1. tympanic membrane 2. malleus 3. incus 4. stapes 5. oval window 6. membranous labyrinth of cochlea

What mechanisms help the brain determine the loudness or volume of the sound entering the ear? (choose all that apply) 1.Hair cells excited at more rapid rate, causing temporal summation. 2.Hair cells on the fringes of the frequency range stimulated, causing spatial summation. 3.The difference between the sound intensities in the 2 ears with the closer ear hearing a noise louder. 4.Stimulation of outer layer of hair cells. 5.The amplitude of the vibration of the basilar membrane. 6.Time lag between entry of sound into one ear and its entry into the other ear. 7. Low frequency sounds cause maximal activation of basilar membrane near the apex of the cochlea. 8. High frequency sounds activate the basilar membrane near the base of the cochlea.

1.Hair cells excited at more rapid rate, causing temporal summation. 2.Hair cells on the fringes of the frequency range stimulated, causing spatial summation. 4.Stimulation of outer layer of hair cells= only when vibration is high

What is the central auditory pathway

1.receptor cell body in spiral ganglion, synapses in brainstem (medulla) in cochlear nerve 2. cell bodies in cochlear nuclei of medulla, decussate and synapse in SON of Pons (superior olivary nucleus of Pons) on same side 3. cell bodies in SON of Pons terminate in midbrain (inferior colliculi) 4. cell bodies in inferior colliculi terminate in thalamus 5. medial geniculate nucleus of thalamus to cerebral cortex (temporal lobe)

Match the type of deafness with its cause(s). __Chronic exposure to loud sounds damages basilar fibers near the apex. __Sensitivity to certain antibiotics damages the Organ of Corti __Old age damages basilar fibers at the base of the cochlea. __Chronic ear infections and otosclerosis scar the ossicles, preventing transmission of vibration 1.High frequency nerve deafness 2.Low frequency nerve deafness 3.All frequency nerve deafness 4.Conduction deafness

2,3,1,4

Match the structure to its description or function. __Communicates with the round window, inferior to the basilar membrane. __Separates the scala tympani from the scala media and contains the organ of corti __Separates the scala media from the scala vestibuli __Bending of hair cells toward this perilymph filled structure causes depolarization __Contains the stria vascularis, which makes endolymph 1. Scala vestibuli 2. Scala media 3. Scala tympani 4. Vestibular Membrane (Reissner's) 5. Basilar membrane

3,5,4,1,2

Match the cell or structure to its description or function. __Contains the gel coating in which the ends of the hair cells are embedded. __About 12,000. Stimulated only when vibration is high, signaling "very loud" to the CNS. __Project upward from hair cells to gel coating, bend toward or away from scala vestibule. __About 3500. Stimulated first, main cell responsible for conducting receptor potential to cochlear nerve endings. __Anchors the basilar fiber to the basilar membrane as it vibrates. 1. Outer hair cells 2. Inner hair cells 3. Stereocilia 4. Tectorial membrane 5. Modiolus

4,1,3,2,5

Reducing the distance between the ossicles but increasing the force of movement is called _______ Question options: The "Place" Principle Attenuation of sound Impedance Matching Vestibulo-ocular reflex

Impedance Matching

What is the place principle?

Nervous system detects sound frequencies by determining positions along basilar membrane that are most stimulated activate specific neurons in response to specific frequencies

What is the receptor for hearing? Question options: Macula of the utricle Rods and Cones Crista ampullaris Organ of Corti

Organ of Corti

Which is FALSE concerning the basilar membrane of the cochlea? a.The basilar membrane separates the scala vestibuli from the scala media b.The basilar membrane contains 20,000-30,000 fibers projecting from the modiolus c.The fibers of the basilar membrane at the base are shorter d.The fibers of the basilar membrane at the base are stiffer e. The Organ of Corti lies on the surface of the basilar membrane

a. The basilar membrane separates the scala vestibuli from the scala media

What happens to the lengths and widths of the basilar fibers as they get farther from the base and closer to the apex? How does this affect the pitch of the sound

lengths of fibers increase from base to apex and decrease in diameter this would lower the frequency

what structures are affected with conductive hearing loss

outer and middle ear trouble getting sound in

How is sound frequency registered in the auditory cortex

there are 6 tonotopic maps in auditory cortex high frequency sounds excite neurons at one end of map, low frequency= excite neurons at opposite ends

How does the difference of endolymph and perilymph contribute to the sensitization of the hair cell?

there's a 80+ millivolts difference between endolymph and perilymph. -150 millivolt intracellular potential in hair cell at top and -70 millivolt potential in hair cell at base This allows the hair cells to be extra sensitized and able to respond to the slightest sound

How is spatial orientation of sound preserved through the auditory pathway?

through 3 spatial patterns for termination of different frequencies to in cochlear nuclei, 2 patterns in inferior colliculi, 1 precise pattern for discrete sound frequencies in auditory cortex