Exam 2 - Audition

Question 1

3 stimulus properties of sound waves

Answer 1

pitch, loudness, timbre

Question 2

Pitch

Answer 2

determined by frequency (Hertz, Hz), cycles per second

Question 3

Loudness

Answer 3

Determined by amplitude (intensity). Greater amplitude means louder sound

Question 4

timbre

Answer 4

determined by complexity and tonal quality. Like knowing the difference between instruments

Question 5

Outer ear

Answer 5

captures, focuses, and filters sound. Has pinna and auditory canal

Question 6

Pinna

Answer 6

Flesh, cartilage ear. sticks out from the side of the head. Captures, funnels, & amplifies sound. Helps w/ localizing sound. Amplifies sound into the Tympanic membrane

Question 7

Auditory canal

Answer 7

channel for sound to travel through

Question 8

Middle Ear

Answer 8

Hollow region behind the tympanic membrane that transfers vibrations. Converts air vibrations into mechanical movement. Important bc inner ear is filled with fluid & more force is needed to move fluid than air. Link between outer & inner ear. Has tympanic membrane, ossicles, oval window, and round window

Question 9

tympanic membrane

Answer 9

aka the eardrum. transmits sound energy to middle ear. Damage to this structure impairs hearing, esp. low
frequency sounds

Question 10

ossicles

Answer 10

“small bones.” convert air vibrations into mechanical movement. Has malleus (hammer) - attached to tympanic membrane, incus (anvil), stapes (stirrup) - bottom presses against membrane behind oval window, info from here to cochlea

Question 11

oval window

Answer 11

opening in the bone surrounding the cochlea. receives vibrations from ossicles (specifically the stapes)

Question 12

round window

Answer 12

membrane separating cochlear duct from middle-ear. Allows fluid in cochlea to move back and forth

Question 13

Inner ear

Answer 13

includes cochlea which has the organ of corti

Question 13

cochlea

Answer 13

Snail-shaped; filled with fluid; surrounded by bone. It important for auditory transduction (where energy transforms from soundwaves to action potentials), contains organ of corti. The cochlea has 3 sections
-Scala vestibuli (entrance stairway)
-Scala media (middle stairway)
-Scala tympani (tympanic stairway)

Question 14

Organ of Corti

Answer 14

receptive organ in scala media. where auditory transduction takes place. The vibratory energy on the oval window causes basilar membrane to bend. Different regions respond to different frequencies of vibrations in the fluid. Consists of 2 parallel membranes and hair cells in between. 1. basilar membrane. 2. Tectorial membrane.

Question 15

auditory transduction

Answer 15

Transforms energy from sound waves into APs (in the cochlea). Analyzes frequency of sound waves. Ex. pitch

Question 16

Hair cells

Answer 16

located in between basilar membrane and tectorial membrane. Hair cells are anchored to the basilar membrane. Cilia are at the top of the hair cell. Synapse on bipolar neurons whose axons make up the auditory/cochlear nerve

Question 17

tectorial membrane

Answer 17

“top shelf” against which the cilia move

Question 18

Auditory transduction

Answer 18

1. Sound waves cause vibrations/movement of basilar and tectorial membrane in cochlea.
2. Cilia of the hair cells bend/are displaced.
3. Receptor Potentials –> increased tension aka cilia movement can depolarize membrane, opening (calcium and potassium) ion channels in the cilia (bc of movement to tallest one). (does not necessarily mean AP is reached).
4. Hair cells form synapses with axons of the cochlear (auditory) nerve bc of depolarization and moving over enough. Auditory nerve can trigger AP
5. Action Potentials sent to the CNS/brain via the auditory nerve

Question 19

Hair cells role in transduction

Answer 19

hair cells are the auditory receptors (similar to dendritic spine of a neuron). They have cilia on them

Question 20

2 types of hair cells

Answer 20

inner - necessary for normal hearing. convert vibrations into electrical signals
outer - influences the effects of sound on the inner hair cells
Both are located on basilar membrane

Question 21

Cilia role in transduction

Answer 21

they are on top of hair cells and arranged according to height (shortest to tallest). Adjacent cilia are linked to each other by elastic filaments links (Tip links). Points of attachment are called Insertional Plaques (point where receptor potentials form!).
If the cilia move towards the tallest one, stretching them, and depolarization happens, opening ion channels.
If the cilia move towards the shortest one, they relax, and hyperpolarization happens, closing ion channels.
The cilia movement stimulates the cells of the auditory nerve

Question 22

Role of auditory nerve in transduction

Answer 22

auditory aka cochlear nerve is a bundle of axons of bipolar neurons that sent auditory info to brain. When hair cells release NT, triggers EPSPs, triggering APs to excite the auditory nerve. Auditory nerve (starts at organ of corti) forms synapses with the medulla (connect with brain)

Question 23

Auditory Pathway Chart

Answer 23

cochlea
auditory nerve
medulla
inferior colliculi (in midbrain)
medial geniculate nucleus (in thalamus)
primary auditory cortex
auditory association cortex

Question 24

Primary auditory cortex

Answer 24

Most info comes from the contralateral ear (but receives info from both ears. Located in the superior temporal cortex. Responds best to tones of a certain frequency.

Question 25

tonotopic representation

Answer 25

Different areas of cells respond best to different frequencies of sound. Same for basilar membrane in cochlea. Tones arranged spatially. Basilar membrane (in cochlea) --> HIGH freq towards BASE. LOW freq towards APEX. Primary auditory cortex --> HIGH freq most represented MEDIALLY (middle), corresponds to BASE. LOW freq represented most LATERALLY (away from middle), corresponds to APEX

Question 26

Auditory association cortex

Answer 26

located under primary auditory cortex. Synthesizes info. There are 2 streams, anterior and posterior.

Question 27

Other names for primary auditory cortex and auditory association cortex

Answer 27

primary auditory cortex = core region. auditory association cortex = belt and parabelt region (transmits signals to other parts of brain)

Question 28

anterior stream and posterior stream

Answer 28

in the association auditory cortex anterior stream - "what" stream. analyzes complex info posterior stream - "where" stream. sound localization

Question 29

Perception of pitch ((freq of sound)

Answer 29

cochlea codes frequencies through place coding and rate coding

Question 30

Place coding

Answer 30

for moderate to high freq. firing of hair cells in diff locations on the basilar membrane code diff frequencies. more concerned with action potentials

Question 31

Rate coding

Answer 31

low frequencies. hair cells at the apex of basilar membrane fire in synchrony with the freq of the sound wave. more about detecting sound wave, are hairs moving

Question 32

perception of loudness

Answer 32

Cochlea codes loudness by action potentials. Moderate to high frequencies --> Louder sounds produce more intense vibrations of the eardrum and ossicles, which produce intense force on the cilia --> makes them release more NTs --> greater firing rate by the cochlear nerve axons. Determined by the RATE of APs from hair cells Low frequencies --> Determined by NUMBER of hair cell axons firing

Question 33

perception of timbre

Answer 33

decipher between pitches (fundamental frequency) and overtones. Diff between sounds like identifying diff instruments

Question 34

fundamental frequency

Answer 34

corresponds to perceived pitch of the note

Question 35

overtone

Answer 35

Frequency of complex tunes that occurs at multiples of the fundamental frequency. Different parts of the basilar membrane respond to each of the overtones. Produces a unique anatomically coded pattern in the cochlear nerve which gets processed by the auditory association cortex

Question 36

hearing loss

Answer 36

decreased sensitivity to sound. most common sensory disability. 1 in 4 older adults; 15% of US population. Causes: damage/loss of auditory system functioning or genetic factors.

Question 37

deafness

Answer 37

loss of hearing where speech perception is lost

Question 38

3 types of hearing loss

Answer 38

conduction deafness, sensorineural deafness, central deafness

Question 39

Conductive deafness (outer/middle ear deafness)

Answer 39

Outer or Middle ear is prevented from transmitting sound waves to the cochlea. Sometimes temporary, can be improved by surgery or hearing aids. Causes: Disease, infection, tumor, issues during development.

Question 40

Otosclerosis

Answer 40

type of cause for hearing loss. Ossicles fuse w/ surrounding bone (small bones fuse together).

Question 41

Sensorineural deafness

Answer 41

aka Nerve deafness (inner ear deafness). Impairs hearing certain frequencies. Damage to cochlea, hair cells, or auditory nerve. Loud noise may damage synapses & neurons in the auditory system. Usually permanent, because damage to organ of Corti, especially hair cells, are irreversible. Treatment may involve cochlear implant. Causes: genetic, infections, disease, exposure to loud noises Listening to sounds over 85-90 decibels for extended periods of time can cause hearing loss. Listening to sounds 110 dB and higher for as little as 30 min can be harmful. Potential treatment involving stem cells to restore hair cell growth.

Question 42

Cochlear implant

Answer 42

Stimulates the auditory nerve. Provides a limited range of frequencies & loudness. Contain microphone, transmitter, wires, electrodes implanted in the basilar membrane. Useful for those who became deaf in adulthood & very young children.

Question 43

Central deafness

Answer 43

Hearing loss caused by brain lesions (ex. stroke, tumor). Complex changes in auditory perception after cortical damage. Can be word deafness or cortical deafness

Question 44

word deafness

Answer 44

People show normal speech & hearing for SIMPLE sounds but cannot recognize spoken words. May be due to abnormally slow auditory inputs

Question 45

cortical deafness

Answer 45

Difficulty recognizing both verbal and nonverbal auditory stimuli. Bilateral damage to the auditory cortex

Question 46

Tinnitus

Answer 46

Frequent or constant ringing in the ears. Damage to the cochlea or other structures in the auditory pathway. Many potential causes: loud noises, medication, various health problems (allergies, tumors, infection)

Question 47

Amusia

Answer 47

Type of auditory agnosia. Tone deafness; inability to produce or comprehend musical sounds. Cannot recognize or differentiate between melodic or rhythmic aspects of music. About 4% of people have congenital amusia. Result from damage to the auditory cortex or prefrontal cortex. Abnormality with the neural networks for music. Poorly understood, people tend to underreport; training makes no difference