(8.1) Auditory Systems Flashcards

1
Q

Sound waves have a…

A

frequency and amplitude

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2
Q

What is Frequency (=pitch)?

A

refers to the speed of vibrations (number of vibrations per second - Hertz, Hz)

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3
Q

What are Rapid vibrations?

A

high frequency = high pitch sound

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4
Q

What are Slow vibrations?

A

low frequency = low pitch sound

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5
Q

What is Amplitude?

A

(=loudness) refers to the size of the vibrations

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6
Q

What are Large vibrations?

A

high amplitude = loud sound

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7
Q

What are Small vibrations?

A

low amplitude = quiet sound

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8
Q

What is Medium?

A

substance that surrounds objects

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9
Q

What is sound?

A

Sound is vibrations of medium (like air or water)

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10
Q

A sound at a single frequency is a…

A

pure tone

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11
Q

A pure tone looks like a…

A

sine wave

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12
Q

Any sound can be created by…

A

summing many pure tones (sine waves) at different frequencies and different amplitudes

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13
Q

any sound can be ‘decomposed’ (taken apart) into…

A

its pure tone components (component frequencies)

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14
Q

The auditory system works by…

A

taking apart sounds into their component frequencies and ‘measuring’ the amplitude of each component

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15
Q

What can the ear be divided into?

A

Divided into outer, middle, and inner

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16
Q

Auditory sensory neurons are located in the…

A

inner ear

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17
Q

What function does the ear have?

A

to amplify sound

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18
Q

The middle ear amplifies sounds so…

A

they can pass from air to water (inside the inner ear)

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19
Q

The eardrum (tympanic membrane) is much larger than…

A

the oval window, giving a proportional amplification

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20
Q

The ear bones (ossicles) act as levers…

A

by magnifying the force of vibrations

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21
Q

Sound makes ear drum…

A

vibrate

22
Q

The inner ear consists of the …

A

cochlea (‘snail’) and the semicircular canals

23
Q

What is the Semicircular canals?

A

part of the vestibular system

24
Q

What is the cochlea?

A

The cochlea is a hollow spiral tube (like a snail)

25
Q

The cochlea contains the…

A

organ of Corti - the sensory organ of hearing

26
Q

The organ of Corti runs along the…

A

length of the cochlea

27
Q

The organ of corti sit between…

A

It sits between the two liquid-filled tubes (scala vestibuli and scala tympani) of the cochle

28
Q

What are hair cells?

A

Hair cells are the sensory neurons of hearing - the neurons that respond to sound vibrations

29
Q

What are the two types of hair cells?

A

There are two types of hair cells, outer hair cells (OHCs) and inner hair cells (IHCs)

30
Q

What do outer and inner haircells form?

A

form two sets of rows along the length of the cochle

31
Q

Bending of the ‘hairs’ (stereocilia) of hair cells pulls…

A

filaments (strings) connecting stereocilia

  • These filaments (tip links) are believed to connect mechanically to ion channels in the hair cells, opening them (like lifting a lid by a string)
  • This causes the hair cells to depolarize and fire action potentials
32
Q

Do hair cells respond fast?

A

Hair cells respond very fast - less than 10 us

33
Q

Fast responding hair cells allow…

A

Allows hair cells to fire in synchrony with sound vibrations but only up to about 3 kHz

34
Q

Different frequencies are instead coded by hair cells preferring different frequencies at…

A

different locations in the cochlea

35
Q

What is tonotopy?

A

Each location along the basilar membrane is most sensitive to one sound frequency -high frequencies near base, low frequencies near tip (apex)

36
Q

Different sounds cause different patterns of activity along…

A

the membrane

37
Q

Only the inner hair cells send out…

A

axons, these are the neurons that respond to sound

38
Q

The outer hair cells (3x as many!) instead receive…

A

neural input from the auditory nerve

39
Q

in response to stimulation, outer hair cells can…

A

contract and modify stiffness of basilar membrane - allowing fine tuning of sound sensitivity (can cause tinnitus)

40
Q

Hair cells are easily damaged by…

A

strong sounds, one cause of deafness

41
Q

Cochlear implants are…

A

electrodes placed inside cochlea that directly stimulate auditory nerve, mimicking function of hair cells

42
Q

Information travels along axons from the inner hair cells…

A

to join to form the auditory nerve

43
Q

When information joins the auditory nerve it….

A

This connects the cochlea with the olive (olivary nucleus) in the brainstem

44
Q

The olive is involved in…

A

Olive is involved in sound localisation

45
Q

What passes through the MGN?

A

Auditory information then passes through the MGN in the thalamus to the auditory cortex

46
Q

Sounds are localised by two mechanisms…

A

Time differences between the ears (<3 kHz) and Intensity differences between the ears (>3 kHz)

47
Q

Time differences between the ears (<3 kHz) are process in…

A

Processed in the medial superior olive (MSO)

48
Q

Intensity differences between the ears (>3 kHz) are processed in…

A

Processed in the lateral superior olive (LSO)

49
Q

Sound information is processed in the…

A

primary auditory cortex, located in the superior temporal lobe

50
Q

Sound localisation utilises…

A

Utilise differences in sound arrival

51
Q

Sound information is processed in the…

A

primary auditory cortex, located in the superior temporal lobe

52
Q

Each sound frequency is represented where?

A

Like in the cochlea, each sound frequency is represented in a different location - tonotopy