Transcript Slide 1

P1.5.3 Sound
Mr D Powell
Connection
•
•
•
Connect your learning to the
content of the lesson
Share the process by which the
learning will actually take place
Explore the outcomes of the
learning, emphasising why this will
be beneficial for the learner
Demonstration
• Use formative feedback – Assessment for
Learning
• Vary the groupings within the classroom
for the purpose of learning – individual;
pair; group/team; friendship; teacher
selected; single sex; mixed sex
• Offer different ways for the students to
demonstrate their understanding
• Allow the students to “show off” their
learning
Activation
Consolidation
• Construct problem-solving
challenges for the students
• Use a multi-sensory approach – VAK
• Promote a language of learning to
enable the students to talk about
their progress or obstacles to it
• Learning as an active process, so the
students aren’t passive receptors
• Structure active reflection on the lesson
content and the process of learning
• Seek transfer between “subjects”
• Review the learning from this lesson and
preview the learning for the next
• Promote ways in which the students will
remember
• A “news broadcast” approach to learning
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Practical Investigation...
1. Take your ruler and investigate the sound wave it
creates by “twanging” it with your fingers. (Take care
not to break it)
2. Think about the relationship between pitch (frequency)
and length.
3. Then make a verbal prediction for what might happen
with a string or tube and draw a diagram.
4. Now test out and write down what you find.
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Draw a circle in your book and write inside it to explain
How a sound wave moves through the air? (1/3rd page)
P1.5.3 Sound
a) Sound waves are longitudinal waves
and cause vibrations in a medium,
which are detected as sound.
NB: Sound is limited to human hearing
and no details of the structure of the
ear are required.
b) The pitch of a sound is determined by
its frequency and loudness by its
amplitude.
c) Echoes are reflections of sounds.
P1.5.3 Sound
Explaining Soundwaves?
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How is Sound Produced... (watch the movie) – RECAP Y9
The vocal folds, also known commonly as vocal
cords, are composed of twin infolding of
Vocal
mucous membrane stretched horizontally
cords
across the larynx.
1. They vibrate, modulating the flow of air
being expelled from the lungs.
2. Open during inhalation, closed when
holding one's breath, and vibrating for
speech or singing.
3. They oscillate 440 times per second when
singing A (above middle C).
Larynx
Trachea
TASK: Imagine you are a doctor talking to
a patient. They have problems talking as
their vagus nerve is damaged. You will
need to explain the mechanics of speech
5. They are white because of scant blood so they understand you. Read the text to
circulation.
help you remember from medicalIndex
school!
4. The folds are controlled via the vagus
nerve.
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How is Sound heard... (watch the movie) – RECAP Y9
The outer ear collects sound
(green). The sound is amplified
through the middle ear (red)
which is hollow, and filled with
liquid, containing a sensory
epithelium that is studded with
hair cells.
The tiny "hairs" from the cells stick
out into the fluid. The hair cells
release a chemical
neurotransmitter when
stimulated. In this way sound
waves are transformed into nerve
impulses. (purple)
The nerve impulses travel to both sides of the brain with the vestibular nerve dealing with
sensing balance.
The human ear can generally hear sounds with frequencies between 20 Hz and 20 kHz (the
audio range).
Index
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a/b) The Trumpet
Trumpet
Chromatic
Scale
Period ms
Bb
C
4
B
C#
277
C
D
293
C#
Eb
311
D
E
329
Eb
F
349
E
F#
F
G
392
F#
Ab
415
3
Frequency Hz Frequency Hz
(Calculated)
250
333
261
370
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a/b) The Real World
A tuning fork produces a note with only
one frequency. The shape of the wave on
the oscilloscope is very smooth.
However, the frequency of the harmonics
in a real instrument may be twice, three
times, four times or even more times the
fundamental frequency.
All these frequencies together make up
the note.
The bottom line here shows the wave
pattern formed by the fundamental and
harmonic frequencies when the note is
played on the instrument.
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a/b Real Sounds
We now know that we can convert
our longitudinal sound wave to a
transverse wave to show on a
screen.
If we look at these three traces of
a middle C note (261Hz) we can
see they are all different but seem
to have similar pattern in terms of
frequency as.......
1 up and 1 down takes (1/261)th
of a second or the length of an
arrow!
clarinet
violin
You need to try an ignore the
funny fluctuations, this is due to
the timbre of the notes – or
richness that some from the
saxophone
instrument itself due to the nature
of the pipes or strings.
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Sound Refraction
BASIC: Just as a submarine can use refraction to hide its acoustic signature from
surface vessels, the same principle of sound refraction can be used to prevent
certain observers from hearing the noise.
FURTHER: For example, an outdoor observer close to the ground will have sound
waves refracted toward him when the ground is cooler than the ambient air and
away from him when the ground is hotter than the air.
IN DEPTH: When the sun warms the Earth’s surface there is a temperature
gradient. The speed of sound decreases as temperature decreases.
The sound wave fronts travel faster near the ground. This means that sound is
refracted upwards away from listeners on the ground creating an “acoustic
shadow” at you move away from the source.
This reverses when the ground is covered with snow or over a lake in the morning.
Underwater this speed depends on pressure (depth), temperature and salinity
allowing submarines to hide in certain sections of water!
http://en.wikipedia.org/wiki/Sound_speed_gradient
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M4. • Q is louder
• Q is higher (pitch/note but not frequency) [if loudness and pitch both
mentioned but direction wrong / absent credit 1 mark]
• louder because bigger amplitude/height
• higher pitch because higher frequency/shorter wavelength/waves closer
together
• factor of 2 mentioned w.r.t either for each • for 1 mark
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Data Trends... (Extension)
Discuss this data with a partner. Can
you see a trend in the numbers?
Can you comment on...
Gas -> Liquid -> Solid
the mass of the molecules or
compounds? (as best you know)
Ethanol
Chloroform
Glass
C2H5OH
CHCl3
SiO2
The bonding or strength of the
structures
You can use the periodic table to
help you?
Think helium and voice box (fixed )
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Speed of Sound
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Speed of Sound

Now try out the experiment as shown. You will
have have to be very accurate to make sure it
works.
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Ultrasound Ranges....
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Ultrasound – HT Questions
As a radiographer it is your task to make measurements
of a foetus while it is in the womb. When you take a
prenatal ultrasound scan, the echo of the pulse of
ultrasound returns in 300 microseconds.
1540 m/s
c = 3 x 108 ms-1
1. If the sound travels at a speed of 1500 m/s in the
fluids of the womb, you can work out the depth of the
tissue that is returning the echo.
1. 1500ms-1 x 150 x 10-6s = 0.225m
2. Ultrasound equipment produces ultrasound with a
frequency between 2MHz and 18 MHz. What are the
wavelengths of ultrasound at these two frequencies?
3. Why does the radiographer not recommend X-rays as
a method of viewing the foetus?
4. Why does she use ultrasound instead?
5. When the ultrasound enters the bladder, the wave
changes direction, producing an image of the organ
on the monitor. What causes this change in the
direction of the wave?
c=f so c/f = 
=1540ms-1/2 x 106Hz
 = 7.7 x 10-4m
or
=1540ms-1/18 x 106Hz
 = 8.6 x 10-5m
http://en.wikipedia.org/wiki/Medica
l_ultrasonography
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