Waves: Sound Waves

Waves: Sound Waves

Types of Waves

  • Sound, like light, is a type of wave that allow us to interpret the world around us.
  • Waves are essential for the transfer of energy without the movement of matter.
  • There are two types of waves: longitudinal and transverse.

Longitudinal Waves and Sound

  • Sound waves are an example of longitudinal waves.
  • Longitudinal waves consist of several compressions and rarefactions.
  • Compression refers to when particles in a medium are pushed closer together.
  • Rarefaction refers to when particles in a medium are spread farther apart.

Properties of Sound Waves

  • The wavelength of a sound wave is the distance between two consecutive compressions or two consecutive rarefactions.
  • Frequency is the number of oscillations per second, measured in Hz.
  • The amplitude of a sound wave determines the volume of the sound.

Speed of Sound

  • Sound travels at different speeds depending on the material it is moving through.
  • In air, sound typically travels at about 343m/s at room temperature.
  • Sound travels faster in solids and liquids because their particles are closer together.

Sound Wave Reflection and Refraction

  • Sound waves reflect off surfaces. This is how echoes are created.
  • Sound waves also refract, or change direction, as they pass from one medium to another.

The Human Ear

  • The ear is an example of an object which uses sound waves.
  • The outer part of the ear, the pinna, collects the sound waves.
  • The waves pass down the ear canal to the eardrum and make it vibrate.
  • These vibrations are passed on to the fluid in the cochlea, which sends signals to the brain.

Sound and Technology

  • Ultrasound waves are sound waves that have a frequency which is higher than humans can hear, typically above 20,000 Hz.
  • They are used in medicine for scans, and in industry for measuring thickness and detection of defects.
  • When these high frequency waves hit a boundary, they create a series of echoes that can be used to build up an image or detect flaws in materials.