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AQA A2 Physics Unit 5B - Medical > Physics of the Ear > Flashcards

Physics of the Ear Flashcards

1
Q

What is the function of the ear?

A

To amplify the small pressure changes and convert them into electrical signals which can be interpreted by the brain.

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2
Q

What is the function of the outer ear?

A

To collect and direct sound into the auditory canal.

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3
Q

What is the function of the middle ear?

A

To transfer the sounds vibrations from the tymphonic membrane to the oval window.

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4
Q

What is the function of the inner ear?

A

To increase pressure produced by the middle ear to produce vibrations that are converted to electrical signals and send them to the brain.

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5
Q

What is the function of the ear canal?

A

To modify the sound through resonance properties.

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6
Q

What is the function of the ear drum?

A

To vibrate when hit by sound waves. (by 10^-11 m)

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7
Q

What are the english names for the bones in the middle ear?

A

Hammer, anvil and stirrup.

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8
Q

What are the latin names for the bones in the middle ear?

A

Malleus, incus and stapes.

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9
Q

What is the collective name for the bones in the middle ear?

A

Ossicles.

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10
Q

What is the function of the ossicles?

A

To amplify sound by a factor of 1.3 and to transfer oscillations to the oval window.

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11
Q

What is the oval window?

A

The entrance to the cochlea.

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12
Q

What is the vestibule?

A

The cavity lying between the oval window and the cochlea.

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13
Q

What is the cochlea?

A

A three-chambered tube filled with fluid.

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14
Q

What are the chambers in the cochlea called and what are they filled with?

A

One is the vestibular chamber which is joined to the tympanic chamber; they are filled with perilymph fluid.

The last is the cochlea duct and that is filled with endolymph fluid.

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15
Q

What are the two fluids in the cochlea called?

A

Perilymph and endolymph.

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16
Q

What separates the cochlea duct and the tymphanic chamber?

A

The basilar membrane.

17
Q

What is the basilar membrane?

A

The membrane that separates the cochlea duct and the tympanic membrane. It supports a layer of sensory hair cells on its inner surface.

18
Q

What is the purpose of the sensory hair cells?

A

They move to the vibrations produced by the waves that travel along the perilymph, and produce electrical signals which are sent to the brain.

19
Q

Define the threshold of hearing.

A

The lowest intensity of sound that can be heard by the ear at 1kHz

20
Q

At which frequency is the normal human ear most sensitive?

A

3000Hz

21
Q

What are the main features of hearing loss?

A

As frequency increases, loss increases.

22
Q

What are the main features of noise related hearing?

A

The loss of hearing is at a maximum at 4kHz.

23
Q

State the main difference between the dB scale and the adapted dBA scale used to measure sound intensity levels.

A

dBA scale is dependent on frequency, dB is not.

24
Q

Sound intensity levels are usually measured in decibels. Why is a logarithmic scale used?

A
  • The ear has a logarithmic response to sound
  • To accommodate a very wide range of sound intensities to which an ear can respond
  • perceived change in loudness is proportional to fractional change in intensity
  • logarithmic scale means that numerical values on the scale represent ratios of two sounds, expressed as the log of that ratio
25
Q

What is the frequency of the threshold of hearing?

A

1 x10^-12

26
Q

What is the unit of the threshold of hearing?

A

Wm^-2

27
Q

Why was it necessary to introduce the dBA scale?

A

It takes account of the frequency dependence of the sensitivity of the ear.

28
Q

Describe the dB graph.

A

flat - same response at all frequencies

29
Q

Describe a dBA graph.

A

most sensitive at 3kHz

crosses dB line at 1kHz

30
Q

How is a dBA graph obtained?

A
  • A sound is listened to at a frequency of 1kHz and intensity level 10dB
  • Same sound is listened to at a different frequency and loudness, loudness is altered.
  • Switch between 1kHz, 10dB and new frequency, new loudness until new loudness is perceived
  • Repeat for frequencies between 20Hz and 14-20kHz
31
Q

Define attenuation and state what causes it.

A

reduction in intensity as a wave travels through a medium due to absorption

32
Q

Define intensity.

A

power per unit cross sectional area

AQA A2 Physics Unit 5B - Medical (5 decks)

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