Transcript Sound - Wsfcs

Sound
Chp. 11 sect.1
The Nature of Sound
Sound
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Sect.
Sect.
Sect.
Sect.
1
2
3
4
The Nature of Sound slides 3-34
Properties of Sound slides 35-56
Music slides 57-72
Using Sound slides 73-81
How Sound Travels
 All sounds are made by something
that vibrates.
How Sound Travels
 All sounds are made by something
that vibrates.
 Sound waves are compressional
 Compression is close together
 Rarefaction is spread out molecules
How Sound Travels
 All sounds are made by something
that vibrates.
 Sound waves are compressional
 Compression is close together
 Rarefaction is spread out molecules
 These areas alternate in a compressional
wave.
How Sound Travels
 Speakers vibrate outward forming
compression
 Speaker vibrates inward forming
rarefaction
How Sound Travels
 Speakers vibrate outward forming
compression
 Speaker vibrates inward forming
rarefaction
 Air molecules around speaker bump
into other molecules; a series of
compressions and rarefactions form a
sound wave
What changes the speed of sound?
 Depends on the
material & whether
it is solid, liquid or
gas
What changes the speed of sound?
 Depends on the
material & whether
it is solid, liquid or
gas
Air C
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m/s
1498 3650 4877
m/s m/s m/s
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What changes the speed of sound?
 Depends on the
material & whether
it is solid, liquid or
gas
 Sound travels
fastest through
solids and slowest
through gases.
Air C
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m/s
1498 3650 4877
m/s m/s m/s
500
m/s
B
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Min
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What changes the speed of sound?
 Depends on the
material & whether it
is solid, liquid or gas
 Sound travels fastest
through solids and
slowest through
gases.
 When molecules are
close, they transmit
energy more quickly.
Air C
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W
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347
m/s
1498 3650 4877
m/s m/s m/s
500
m/s
B
R
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k
A
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Min
um
What changes the speed of sound?
 Loud and soft sounds travel through a
material at the same speed.
What changes the speed of sound?
 Loud and soft sounds travel through a
material at the same speed.
 The closer the molecules are to each
other, the faster they can transfer
energy.
What changes the speed of sound?
 Loud and soft sounds travel through a
material at the same speed.
 The closer the molecules are to each
other, the faster they can transfer
energy.
 As temperatures increase, molecules
move faster.
How your ears allow you to hear
 Making sense of sound waves:
 1) Ears gather compressional waves
How your ears allow you to hear
 Making sense of sound waves:
 1) Ears gather compressional waves
 2) Amplify the waves
How your ears allow you to hear
 Making sense of sound waves:
 1) Ears gather compressional waves
 2) Amplify the waves
 3) Changed waves to nerve impulses
How your ears allow you to hear
 Making sense of sound waves:
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1)
2)
3)
4)
Ears gather compressional waves
Amplify the waves
Changed waves to nerve impulses
Brain translates nerve impulses
How does the outer ear gather
waves?
 Outside of ear with
the ear canal and
the eardrum make
up the outer ear.
How does the outer ear gather
waves?
 Outside of ear with the
ear canal and the
eardrum make up the
outer ear.
 Eardrum is a tough
membrane stretched
over the end of the ear
canal which vibrates
when sound waves
reach it.
What does the middle ear do?
 Three tiny bones,
hammer, anvil &
stirrup make the
vibrations stronger.
What does the middle ear do?
 Three tiny bones,
hammer-2, anvil-3
& stirrup-4 make
the vibrations
stronger.
 This lever system
makes the force &
pressure of the
sound waves
stronger.
What does the middle ear do?
 Three tiny bones, hammer, anvil &
stirrup make the vibrations stronger.
 This lever system makes the force &
pressure of the sound waves stronger.
 The stirrup connects to a membrane
in the oval window which vibrates as
the stirrup does.
What does the inner ear do?
 Cochlea spiralshaped structure,
liquid-filled,
contains tiny hair
cells.
What does the inner ear do?
 Cochlea spiralshaped structure,
liquid-filled,
contains tiny hair
cells.
 When hair cells
vibrate, nerve
impulses are sent
to brain
What does the inner ear do?
 Cochlea spiral-shaped structure,
liquid-filled, contains tiny hair cells.
 When hair cells vibrate, nerve
impulses are sent to brain
 Cochlea changes sound waves to
nerve impulses.
What does the inner ear do?
 Cochlea spiral-shaped structure,
liquid-filled, contains tiny hair cells.
 When hair cells vibrate, nerve
impulses are sent to brain
 Cochlea changes sound waves to
nerve impulses.
 If hair cells are damaged or destroyed
by loud sounds, person can lose
ability to hear.
Object creates vibrations which are
transferred through the air by
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Where they are made stronger by the
hammer
And transmitted into the
Where the
Change them into brain waves
Object creates vibrations which are
transferred through the air by
Sound waves travel
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Where they are made stronger by the
hammer
And transmitted into the
Where the
Change them into brain waves
Object creates vibrations which are
transferred through the air by
Sound waves travel
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Ear drum
Where they are made stronger by the
hammer
And transmitted into the
Where the
Change them into brain waves
Object creates vibrations which are
transferred through the air by
Sound waves travel
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Ear drum
Where they are made stronger by the
anvil
hammer
And transmitted into the
Where the
Change them into brain waves
Object creates vibrations which are
transferred through the air by
Sound waves travel
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Ear drum
Where they are made stronger by the
stirrup
And transmitted into the
anvil
hammer
Where the
Change them into brain waves
Object creates vibrations which are
transferred through the air by
Sound waves travel
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Ear drum
Where they are made stronger by the
stirrup
And transmitted into the
anvil
hammer
Inner ear
Where the
Changes them into brain waves
Object creates vibrations which are
transferred through the air by
Sound waves travel
Compressions
To the outer ear, then transmitted through the
Ear canal
To the
Ear drum
Where they are made stronger by the
stirrup
And transmitted into the
anvil
hammer
Inner ear
Where the
cochlea
Changes them into brain waves
Properties of Sound
Sound Section 2
Properties of Sound
 How amplitude, intensity, & loudness
are related
 How sound is measured
 The relationship between frequency
and pitch
 The Doppler effect
How amplitude, intensity, &
loudness are related
 Intensity is the
amount of energy
that flows through
a certain area in a
specific amount of
time.
How amplitude, intensity, &
loudness are related
 Intensity is the
amount of energy
that flows through a
certain area in a
specific amount of
time.
 Turning down
volume reduces the
energy carried by
the sound waves and
its intensity.
How amplitude, intensity, &
loudness are related
 Intensity affects how far a wave will
travel.
How amplitude, intensity, &
loudness are related
 Intensity affects how far a wave will
travel.
 Low intensity loses energy quickly
 High intensity travels farther
How amplitude, intensity, &
loudness are related
 Loudness is the way humans
understand sound intensity.
 High intensity sounds make your
eardrums vibrate further which in turn
creates increased hair cell movements
making you hear a loud sound instead of
quiet one.
How is sound measured?
 Loudness or intensity of sound is
measured in decibels (dB).
How is sound measured?
The relationship between frequency
and pitch
 Pitch is how high or low a sound
seems to be and is related to
frequency of the sound waves.
The relationship between frequency
and pitch
 Frequency, measured in Hertz (Hz),
refers to the number of wavelengths
that pass by in 1 second.
The relationship between frequency
and pitch
 Frequency, measured in Hertz (Hz),
refers to the number of wavelengths
that pass by in 1 second.
 High frequency means many
compressions hit your ear each second
resulting in high pitch
The relationship between frequency
and pitch
 Frequency, measured in Hertz (Hz),
refers to the number of wavelengths
that pass by in 1 second.
 High frequency means many
compressions hit your ear each second
resulting in high pitch
 Low freq. mean low pitch, less
compressions
Human hearing
 A healthy human ear can hear sound
waves from 20 to 20,000 Hz.
Human hearing
 A healthy human ear can hear sound
waves from 20 to 20,000 Hz.
 Best hear sounds b/w 440 – 7,000 Hz
Human hearing
 A healthy human ear can hear sound
waves from 20 to 20,000 Hz.
 Best hear sounds b/w 440 – 7,000 Hz
 Ultrasonic frequencies above 20,000
Hz cannot be heard by humans.
Dogs hear up to 35,000 Hz. Bats hear
beyond 100,000 Hz.
Human hearing
 A healthy human ear can hear sound waves
from 20 to 20,000 Hz.
 Best hear sounds b/w 440 – 7,000 Hz
 Ultrasonic frequencies above 20,000 Hz
cannot be heard by humans. Dogs hear up
to 35,000 Hz. Bats hear beyond 100,000
Hz.
 Infrasonic or subsonic waves have freq.
below 20 Hz like wind, heavy machinery,
earthquakes…can be felt not heard
Doppler Effect
 Change in pitch
or frequency
because a wave
source is
moving.
Doppler Effect
 It is also noticeable
when you are
moving past a
sound source that
is standing still.
 The faster the
change in position,
the greater the
change in
frequency & pitch.
How is the Doppler Effect used?
 Radar guns measure speed of cars
 Weather radar tracks wind in storms
Intensity, high-amplitude,
ultrasonic, decibel, subsonic, freq.
 ____ sound frequencies are too high
for humans to hear. As the ___ of a
sound wave increases, the pitch
increases. In a ___ sound wave, the
compressions are dense. The ___ is
the unit for measuring how intense a
sound is. As the ___ of a sound wave
increases, the loudness increases.
Another name for infrasonic is ___.
Intensity, high-amplitude,
ultrasonic, decibel, subsonic, freq.
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sound frequencies are too high
for humans to hear. As the frequency of a
sound wave increases, the pitch
increases. In a high-amplitude sound wave,
the compressions are dense. The decibel
is the unit for measuring how intense
a sound is. As the intensity of a sound
wave increases, the loudness
increases. Another name for
infrasonic is subsonic.
Ultrasonic
Music
Sound section 3
Music
 The difference between noise & music
 Why different kinds of instruments
sound differently
 How instruments make music
 How beats are made
Music
 Noise has random patterns and
pitches.
 Music is made up of sounds that are
carefully chosen and have regular
patterns.
Natural frequencies
 Every material will vibrate at its
natural frequencies dependent upon:
 Thickness
 Length
 Tightness
Every musical instrument…
 Contains something that vibrates at
its natural frequencies to create a
pitch.
 Strings- guitar, violin
 Membrane- drum
 column of air- flute, oboe
Resonance
 The ability of a medium to vibrate by
absorbing energy at its own natural
frequency.
 Resonance helps amplify the sound of
many musical instruments.
Sound Quality
 Describes the differences among
sounds of the same pitch and
loudness.
 Each instrument has its own sound
quality.
 Main tone that is played & heard is
called the fundamental frequency.
Overtones
 Vibration with a frequency that is a multiple
of the fundamental.
Overtones
 Suppose a guitar vibrates at a
fundamental frequency of 250 Hz.
Multiples of 250 are 500 Hz, 750 Hz,
1000 Hz and so on.
 Overtones create the rich sounds of a
guitar.
 Every instrument has a different
number & intensity of overtones.
How do string instruments produce
sound?
 Plucking, striking, or moving a bow
across a string produces sound.
How do string instruments produce
sound?
 Plucking, striking, or moving a bow
across a string produces sound.
 A resonator is a hollow space filled
with air that makes sound louder
when the air inside it vibrates.
How do string instruments produce
sound?
 Plucking, striking, or moving a bow
across a string produces sound.
 A resonator is a hollow space filled
with air that makes sound louder
when the air inside it vibrates.
 Ex. Violins, electric guitars, harps
What about brass & woodwinds?
 Brass have a cone-shaped mouthpiece
inserted in a metal tube resonator which
produces a pitch
How do percussion instruments
make sound?
They are hit, shaken or rubbed to produce sound.
Musical Instruments
flute
String instruments
Wind instruments
Percussion
instruments
cymbal
Electric guitar
Musical Instruments
flute
oboe
violin
Electric guitar
String instruments
Wind instruments
horn
harp
cello
trombone
Percussion
instruments
Steel drums
cymbal
Bass drum
xylophone
Using sound
Sound Section 4
What You’ll Learn
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What affects sound in a concert hall
How some animals use sound waves
How sonar is used
About ultrasound
What affects sound in a concert hall
 Reverberation is the echoing
produced by many reflections of
sound that make it difficult to hear
clearly.
 Acoustics is the study of sound.
 Soft materials like carpet and drapes
can reduce reverberations.
Echolocation
 Process of locating objects by making
sounds and interpreting the sound
waves that reflect or bounce back
Sonar
 A system that uses
reflections of
underwater sound
waves to detect
objects.
Sonar
 A system that uses
reflections of
underwater sound
waves to detect
objects.
 A hydrophone picks up
the reflected sound.
Since the speed of
sound in water is
known, the distance
can be found by
measuring time.
Ultrasonic waves
 Can also be used to clean delicate
items like jewelry
Ultrasonic waves
 Can also be used to clean delicate
items like jewelry
 Can be used to make images of soft
body parts without doing surgery
Ultrasonic waves
 Can also be used to clean delicate
items like jewelry
 Can be used to make images of soft
body parts without doing surgery
 Kidney stones and gallstones can be
broken up with ultrasound treatments