Sound Waves and Hearing

• What are sound waves essentially made of?

  Vibrations passing through molecules
• How do sound waves travel through materials?

  As a series of compressions and rarefactions
• What are compressions in sound waves?

  Regions where particles are closest together
• What are rarefactions in sound waves?

  Regions where particles are furthest apart
• How do sound waves travel through solids?

  By causing particles to vibrate and collide
• Why do sound waves travel faster in solids?

  Because particles are more densely packed
• Why can't sound travel through a vacuum?

  There are no particles to vibrate through
• What happens to sound waves' frequency when they pass between different mediums?

  Frequency remains unchanged
• What does the equation speed = frequency × wavelength imply when speed increases?

  Wavelength must increase if frequency is constant
• How does wavelength change in higher density mediums?

  Wavelength gets longer as sound speeds up
• What happens to wavelength in low density materials like air?

  Wavelength gets shorter as sound slows down
• What phenomenon occurs when sound changes speed between mediums?

  Sound can be refracted
• How does sound behave with hard flat surfaces?

  It reflects most, creating echoes
• What are the main parts of the human ear involved in hearing?

  • Ear canal
  • Eardrum
  • Ossicles (three small bones)
  • Semicircular canals
  • Cochlea
  • Auditory nerve
• What happens when sound waves reach the ear?

  They travel along the ear canal to the eardrum
• What does the eardrum do when sound waves hit it?

  It vibrates in response to the sound waves
• How are vibrations transmitted after the eardrum vibrates?

  Through the ossicles to the cochlea
• What does the cochlea do with the vibrations?

  It converts them into electrical signals
• How does the brain interpret the electrical signals from the cochlea?

  As sounds with varying pitches and volumes
• What is the typical human hearing range?

  20 hertz to 20,000 hertz
• How does age affect human hearing range?

  It normally decreases due to wear and tear
• What causes the decrease in hearing range as we age?

  Wear and tear of the cochlea and auditory nerve
• What are the key functions of the ear structures in hearing?

  • Ear canal: directs sound waves
  • Eardrum: vibrates with sound waves
  • Ossicles: transmit vibrations to cochlea
  • Cochlea: converts vibrations to electrical signals
  • Auditory nerve: sends signals to the brain