PHY2227: Medical & Health Physics
Assignment #7 is due on Thursday May 01, 2014 at 5 p.m.
1.
Bats detect the obstacles in their path by receiving the reflected ______
(a)
infrasonic waves
(b)
radio waves
(c)
electro-magnetic waves
(d)
ultrasonic waves
2.
Which of the following lists the correct order of events leading to a sound being
"heard" by a person?
3.
I
II
III
The fluid-filled inner ear moves hair cells, which send signals to the brain.
The eardrum vibrates at the frequency of the sound waves entering the ear.
The bones of the middle ear, which are attached to the eardrum, start to
move, pushing on the oval window.
(a)
(b)
(c)
(d)
II, III, I
I, II, III
II, I, III
III, I, II
Which is NOT true about sound?
(a)
soft materials are good sound absorbers
(b)
as a car accelerates the pitch of the engine increases
(c)
light travels much faster than sound
(d)
eardrums cannot be permanently damaged by continuous moderately loud
sounds
Use the following table to answer Questions 4 and 5.
ANIMAL
Sheep
Cat
Dog
Human
Dolphin
Bat
4.
LOWEST
100
45
67
64
200
2000
HIGHEST
30000
64000
45000
23000
150000
110000
Which animal has the smallest frequency range of hearing?
(a)
Human
(b)
Cat
(c)
Bat
(d)
Dolphin
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5.
Which animal has the largest frequency range of hearing?
(a)
Human
(b)
Cat
(c)
Bat
(d)
Dolphin
The following graph represents the Sound Level safety Limits. Use it to answer
Questions 6 to 8.
6.
What is the maximum sound level in decibels, you should be exposed to for 6
hours?
(a)
92 dB
(b)
93 dB
(c)
95 dB
(d)
97 dB
7.
If you are exposed to a maximum sound level of 100 decibels, what is exposure
time in hours?
(a)
2 hours
(b)
4 hours
(c)
6 hours
(d)
8 hours
8.
What is the maximum safe time you should be exposed to a sound level of
95dB?
(a)
4½ hours
(b)
4¼ hours
(c)
4 hours
(d)
3¾ hours
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9.
The frequency which is not audible to the human ear is:
(a)
50 Hz
(b)
500 Hz
(c)
5000 Hz
(d)
50000 Hz
10.
The vibrations or the pressure variations inside the inner ear are converted into
electrical signals by the_________
(a)
Cochlea
(b)
Tympanic
(c)
Pinna
(d)
Anvil
11.
Vibrations inside the ear are amplified by the three bones namely the _________
in the middle ear.
(a)
hammer, anvil and stirrup
(b)
hammer, anvil and pinna
(c)
hammer, cochlea and stirrup
(d)
auditory bone, anvil and stirrup
12.
The membrane that separates the outer ear from the middle ear of mammals is
called the
(a)
basilar membrane
(b)
tympanic membrane
(c)
oval window
(d)
tectorial membrane
13.
Compared with chemical stimuli, auditory stimuli
(a)
travel farther
(b)
travel more quickly
(c)
provide better directional information
(d)
all of the above
14.
The Eustachian tube connects the
(a)
outer ear and middle ear
(b)
middle ear and inner ear
(c)
inner ear and throat
(d)
middle ear and throat
15.
Which of the following sensory receptors function via hyperpolarization rather
than depolarization?
(a)
rod and cone cells
(b)
organs of Corti
(c)
proprioceptors
(d)
all of the above
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16.
Which of the following is not one of the ossicles in the middle ear of humans?
(a)
Stirrup
(b)
Anvil
(c)
Saddle
(d)
Hammer
17.
In the cochlea, the hair cells are contained by the
(a)
tectorial membrane
(b)
tympanic membrane
(c)
basilar membrane
(d)
vestibular membrane
18.
The human inner ear is where sound waves are amplified by means of the
vibrations of tiny bones.
(a)
True
(b)
False
SECTION B
Answer Question 17 OR Question 18
17.
18.
(a)
With reference to the structure of the ear, explain how it:
(i)
responds to an incoming sound wave.
(ii)
adjusts to very loud sound;
(ii)
adjusts to very quiet sounds.
(b)
The ear is said to have a logarithmic response to intensity.
(i)
Explain what this expression means;
(ii)
Calculate the intensity level of a sound of intensity 5.1 x 10–5Wm–2
given that the threshold intensity is 1.00 x 10–5Wm–2.
(c)
When people are suffering from a cold they often experience discomfort in
their ears in an aircraft. Explain why this occurs and what they could do to
help reduce the pain.
(d)
To ensure that someone can hear a conversation you raise your voice by
15dB. Determine the change in sound intensity.
(a)
Describe the three main parts of the ear and explain their contributions to
the process of hearing.
(b)
There are two common causes of hearing loss in adults. Explain what
these two types are and suggest whether a hearing aid can help these
problems.
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(c)
A cyclist and a railway train are approaching each other. The cyclist is
moving at 50ms–2 and the train at 30ms–2. If the train sounds a warning
siren at a frequency of 500Hz, calculate the frequency of the note heard by
the cyclist:
(i)
before, and
(ii)
after the train has passed by.
(Assume the speed of sound in air = 340ms–2.)
(d)
A sound of intensity 10–6Wm–2 corresponds to normal conversation.
Calculate the sound level in decibels by assuming that the threshold of
hearing is 10–12Wm–2.
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