Intensity Determines Loudness Sect. 16-3. How is Amplitude Related to Loudness? Pg 533 How did the loudness of the sounds compare? How is amplitude related.
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Intensity Determines Loudness
Sect. 16-3
How is Amplitude Related to Loudness? Pg 533 How did the loudness of the sounds
compare? How is amplitude related to loudness? Challenge: Using what you learned
from experimenting with the rubber band, explain why swinging a drumstick harder on a drum would make a louder sound than swinging a drumstick lightly.
Intensity determines loudness.
SECTIONOUTLINESECTIONOUTLINE
intensity
decibel
amplification
acoustics
A sound wave with a lower amplitude and energy is perceived as a softer sound.
16.316.3
CHAPTERRESOURCESCHAPTERRESOURCES
Intensity determines loudness.
SECTIONOUTLINESECTIONOUTLINE
intensity
decibel
amplification
acoustics
A sound wave with a higher amplitude and energy is perceived as a louder sound.
16.316.3
CHAPTERRESOURCESCHAPTERRESOURCES
Intensity determines loudness.
SECTIONOUTLINESECTIONOUTLINE
intensity
decibel
amplification
acoustics
A sound wave with a higher amplitude and energy is perceived as a louder sound.
16.316.3
VISUALIZATION
Discover how particles move as sound waves move through the air.
CHAPTERRESOURCESCHAPTERRESOURCES
The more energy a sound wave carries, the more intense it is and the louder it will sound.
The intensity of a sound is the amount of energy its sound wave has.
A unit called the decibel(dB) is used to measure sound intensity
Amplitude is also a measure of wave energy; The greater the amplitude, the more intensity a sound wave has and the louder the sound will be.
Approximate Sound Intensities pg. 534 At more than 100 decibels sounds
become very loud. What is the source of the most
intense sound in the picture? What is the source of the least
intense sound in the picture?
Why is it harder to hear a person talking far away from you than someone who is closer to you?Sound waves spread out from their source in all directions.
As they spread out, their energy spreads out, so the
loudness decreases.
Controlling the Intensity of Sound As the amplitude of a sound
decreases, the frequency stays the same.
Change intensity without changing its quality by taking energy away from or adding energy to a sound wave.
Sound intensity can be controlled in many ways. Ex) muffler
Amplification Increases the strength of an
electrical signal. Often used to increase the
intensity of a sound wave. Experienced when you listen to a
t.v., radio, or stereo.
Amplification When the frequency of an applied
force matches the natural frequency of a system, large amplitude vibrations results in what’s called resonance.
Resonance explains why a glass shatters at a pitch that matches its natural frequency.
Amplification in a Stereo Sound input comes from a microphone
in the form of weak electrical signals Transistors turn these signals into
stronger ones, which are converted into vibrations in a coil in the speakers.
The coil is attached to a cone, which vibrates and sends out sound waves.
Acoustics Involves how sound is produced Involves how sound is received and
heard Refers to the way sound waves
behave inside a space.
Compare and Contrast p.535 Imagine sound waves reflecting off
the surfaces in the two photographs.
How do the reflections differ? How would the addition of sound
absorbing materials affect sound?
Intense sound can damage hearing Damage and destroy the hair cells
inside the ear Ear damage can be lessened by
wearing ear protection, such as ear plugs, or by covering the ears.
If the damage is slight, injured cells might be repaired, but such delicate cells could be permanently damaged.
Sound has many uses.
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sonar
echolocation
16-4: Human uses of sound:
sonar
ultrasound
music
telephone
recording
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Sound has many uses.
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sonar
echolocation
Bats use sound to locate objects.
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Objects that can be detected by ultrasound
Food sources Objects underwater Inside of the body
Echolocation Sending out of ultrasound waves
and interpreting the returning echo.
Bats use sound to locate objects
Explore Echoes: How did sound change when you
added the book? How can an echo be used to detect
an object?
Explore Echoes: How did sound change when you
added the book? The sound was louder with the book than without the book.
How can an echo be used to detect an object? An echo can be used to detect an object by reflecting off the object. If there is no object to reflect off, there would be no echo.
Sonar Instruments that
use echolocation to locate objects
Stands for sound navigation and ranging
Can detect sounds from submarine propellers
Can locate underwater objects
Can find schools of fish
Can be used to map the ocean floor
Can be used to find sunken ships
Ultrasound can be safely used on humans
Ultrasound waves cannot be heard by humans, so they can be used on humans at very high intensities without damaging hearing.
Medical Uses of Ultrasound Examine internal organs Check the health of a fetus during
pregnancy. Can break up kidney stones
Sound waves can produce music – Characteristic sounds of instruments
All of the pitches of the instrument, along with the resonance of the instrument itself, produce the characteristic sound of the instrument.
Changing the pitch of a drum Loosen or
tighten the drum skin
While playing a particularly long and loud song on your guitar, it may become out of tune.
What has happened is that the strings have loosened and the pitch has changed.
Two inventions in the late 1800s that changed the world of sound
Telephone phonograph
How telephones transmit your voice to another telephone As you speak into the mouthpiece, your
sound waves cause a thin disk inside to vibrate.
A microphone turns these vibrations into electrical signals.
These signals are sent over wire to a switching station.
Computers connect the wire to the other telephone.
How Edison’s Phonograph machine worked Edison’s phonograph had a needle
connected to a diaphragm that could pick up sound waves.
The vibrations of the sound waves were sent to the needle, which cut into a piece of foil.
To play back the sound, Edison used another needle to track along the grooves made in the foil.
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