Sound (Audition)

Question 1

Audition

Answer 1

1. stimulus (pressurized sound wave)

2. hair cell ( specialized receptor)

Question 2

pressurized sound wave

Answer 2

• air molecules are compressed–> pressurized
• pressure tries to escape out where it can and creates areas of high and low pressure = sound waves
• different frequencies can be added together
• lower frequency sounds travel farther

Question 3

pathway

Answer 3

• sound waves travel and hit outer visible part of ear “pinna”
• funneled by pinna and through auditory canal (external auditory meatus)
• hit eardrum, which vibrates and causes 3 bones to vibrate (malleus, incus, stapes)
• stapes attached to oval window (starts to vibrate)
• oval window attached to cochlea, and when it vibrates, causes fluid to moved through to tip of cochlea–> then goes back and to the round window
• eventually fluid stops moving
• hair cells in cochlea are pushed back and forth which send electrical impulses to brain via auditory nerve to brain

Question 4

organ or corti

Answer 4

• membrane along cochlea that prevents fluid from going back to oval window after it moves to tip of cochlea
• composed of basilar membrane and tectorial membrane
• outermost part of ear

Question 5

external ear

Answer 5

• includes pinna, external auditory meatus, to tempanic membrane and eardrum

Question 6

middle ear

Answer 6

• malleus, incus, stapes

Question 7

inner ear

Answer 7

• cochlea and semicircular canal

Question 8

cochlea and inner ear

Answer 8

• round snail like structure
• unravels flat
• stapes bone connected to other two bones and eardrum
• stapes connected to oval membrane called elliptical window- gets pushed in and out as stapes moves
• fluid inside cochlea that gets pushed around cochlea when elliptical window pushes
• organ of corti separates the cochlea in two
• as fluid compresses, window gets pushed out

Question 9

hair cells

Answer 9

• located on upper and lower membrane (corti)
• fluid flow around organ of corti–> pushes down on one membrane, pushes up on the other–> causes hair cells to move (vibrate)
• sharp thin part of hair cell- filaments (kinocilium) form hair bundle, kinocilium are connected by tip links
• tip link- attached to gate of K+ channel, so as hair cells get pushed around, the kinocilium gets stretched and gate opens, K+ and Ca+ into cell–> fires AP–> activates spiral ganglion cell–> brain

Question 10

auditory processing

Answer 10

• distinguishing frequencies 20-20000Hz
• uses cochlea and basilar tuning (brain can differentiate between high and low frequency)- tonotypical mapping
• hair cells at base activated by high frequency sounds
• hair cells at apex of cochlea activated by low frequency sounds
• -> AP to primary auditory cortex

Question 11

primary auditory cortex

Answer 11

• region of brain responsible for receiving information from the cochlea
• separated if frequency

Question 12

cochlear implants

Answer 12

• surgical procedure to restore ability to hear
• sensorineural hearing loss- nerve deafness
• normally have sound waves that hit ear and travel through auditory canal, that causes vibration of 3 bonds, and fluid moves to stimulate hair cells that produce electrical signal to brain
• w/ hearing loss, there is a problem with conduction
• implant has receiver (receives information from transmitter that gets electrical information from a speech processor that converts sounds from microphone) and stimulator–> cochlea converts electrical impulse into a nerve impulse