What is sound?

Sound is very important for hearing people.
It is mainly used:

• For communication
  (Speech and Hearing)
• Entertainment and leisure
  (Music, radio, TV and film, ...)
• A warning signal
  (Car horn, overwegbel, fire alarm, ...)
• Noise as a nuisance
  (Explosions, traffic, crowds, ...)
• And soothing background
  (Music, rolling sea, babbling brook, ...)

Sounds are vibrations of air. By definition, a variable sound pressure in air, which propagates as a wave. We talk about noise, then we usually mean "hear" sound. However, there are many "inaudible" sounds impossible to perceive the normal limits of human hearing capacity or hearing.

Sound is the experience that informs our ears, very small and rapid changes in air pressure, arising from a sound source, and further propagated. Examples are the shaky legs of a tuning fork, the strings of a piano or guitar, the vibrating vocal cords in singing or speaking, ...

If these pressure variations reach the ear of man, they are through the ear canal to the eardrum. The eardrum starts to vibrate and sends the generated vibrations through the middle and inner ear to the brains, where the sound can be perceived and interpreted.

Sound waves have two main characteristics: height, length and amplitude, wavelength