Transcript Sound

Class Starter
(Copy and answer)
1. What type of waves are sound
waves? Be specific.
2. How can you protect your
hearing?
Sound
Chapter 21
Nature of Sound
• Caused by vibrations of molecules.
• Requires a medium.
• Classified as a mechanical,
longitudinal wave.
• Acoustics  science of sound
Nature of Sound
• Speed of sound = 340 m/s in air
(760 mph)
• Speed varies with temperature &
altitude
• Sound travels faster in liquids and
solids because molecules are
closer.
Properties of Sound
1. Intensity
• Amount of energy in a wave
(amplitude)
• Determines the volume.
• Metric Unit  Decibel (dB)
Decibel Ranges
Breathing
10 dB
Vacuum 70 dB
Library 40 dB
Ticking of
a clock
30 dB
Blender 90 dB
Rock
Concert
115 dB
Thunder
120 dB
Threshold of Jet Take off
pain 130 dB
140 dB
Shuttle Take
off 190 dB
Properties of Sound
2. Pitch
• How high or low the sound is.
• Relates to frequency.
Frequency
Pitch
High 
High
Low 
Low
Properties of Sound
• Humans can hear between 20 –
20,000 hertz
– Infrasonic  too low to hear
• Ex. Earthquake
– Ultrasonic  too high to hear
• Dog whistle
Properties of Sound
• Doppler Effect  A noticeable
change in pitch due to the
position of an object.
• As the sound approaches  high
pitch.
• As the sound leaves  low pitch.
Uses of Sound
• Communication
• Entertainment
Uses of Sound
• Medicine
Uses of Sound
• Weather Forecasting
Uses of Sound
• Sonar
Uses of Sound
• Echolocation
Class Starter
1. What is the purpose of your outer
ear?
2. Where are the 3 smallest bones
in the human body located? Can
you name them?
The Human Ear
• Consists of 3 parts
1. Outer Ear
• Collects sound
2. Middle Ear
• Amplifies sound (makes it
louder)
The Human Ear
• Consists of 3 parts
3. Inner Ear
• Converts sound into nerve
impulses.
The Human Ear
Outer ear
stirrup
anvil
hammer
Semicircular canals
Auditory Nerve
cochlea
Ear drum
Ear canal