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What are the
properties of sound?
Chapter 12: Lesson 2:
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Play a guitar.
What do you hear?
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Is a type of energy we hear.
Sound
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Moves quickly back and forth.
Vibrates
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Compression
Rarefaction
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Outer ear
Middle ear
Inner ear
Ear drum
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Sound Waves
Vibrations that move through matter
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Direction of sound
Direction of energy
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Sound waves moves in the same direction the energy is
moving in.
Longitudinal Waves
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Waves that move in a different direction.
Transverse Waves
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Sounds travel through 3 media.
- Sound travels through the solid the fastest(energy passed through closely packed particles)
- Sound travels through the gases the slowest.
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What is an echo?Echo are sound waves that are reflected back.
(When the sound wave hits a flat, firm surface)
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How can echo or noise be reduced?
By covering the room with soft, thick, uneven material.
Wall paddingFloor foam Wood panels Wall art
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How does covering rooms with the above materials help?
When a sound wave hits the material the sound is absorbed (changes to thermal energy).
Absorption:Transfer of energy when a wave disappears into a surface.
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Frequency
The number of times an object vibrates per second.
Unit:Hertz (Hz).
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Musical notes can be:
High notes Low notes
How high or low sound is.
Pitch
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Low pitch sounds has
lower frequency.
High pitch sounds has
higher frequency.
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Is there a difference between pitch and
frequency?YES!!!
Pitch is the way our ears hear sound.(The way we hear sound is related to the number of peaks BUT, they are not the
same thing)
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How to change pitch?
High pitch
Short guitar string
Vibrates fast causing high pitch
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Low pitch
Long guitar string
Vibrates slowly causing low pitch
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If you are standing still the sound waves will sound normal
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If the source of sound is moving towards you, you will hear more vibrations.
So the sound you are hearing
becomes high pitched.
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If the source of sound is moving away from you, you will hear less vibrations.
So the sound you are hearing becomes low pitched.
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When sound frequency changes due to moving towards or away from the sound.
The Doppler effect.
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When you are TALKING the sound waves will look like this
When you are SCREAMING the sound waves will look like this
When you are WHISPERING the sound waves will look like this
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Amplitude
How dense is the air during compressions and rarefactions.
Units:Decibels (dB)
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Humans hearing range.