How Sound Travels

1
How Sound Travels

• Sound is a mechanical wave
• It moves by vibrating particles in
• Solids
• Liquids
• Gases
• Sound can not travel in a vacuum (empty space)!!!

• Speed of sound is affected by material
• Solids- fastest
• Gases slowest
• Speed of sound is affected by temperature
• Higher temp. faster
• Lower temp. - slower

2
Pitch

• Pitch is determined by the frequency of the sound
  wave
• Low frequency low pitch
• High frequency high pitch

• Pitch is measured in Hertz (waves per second)
• Infrasound lower pitch than detected by human
  ear
• Ultrasound higher pitch than detected by human
  ear

3
Intensity

• Intensity is determined by the amplitude of the
  sound wave
• High amplitude high intensity
• Low amplitude low intensity

• Intensity is measured in decibels
• Sounds greater than 90 decibels can damage
  hearing
• Sound intensity can be controlled
• Muffling
• Amplification

4
Uses of Sound Waves

• In the medical field
• Ultrasound is used to get images of inside the
  body
• In communications
• Telephones, radios
• Sonar
• Used by ships, submarines to navigate

• In nature
• Bats, porpoises, whales and other animals use
  echolocation
• To make music
• Stringed instruments
• Wind instruments
• Percussion instruments