• Background
  • Instructions
  • Illustration
  • Quiz

Background

If you recall, when examining what light is, we talked about light as a wave. In examining waves, there are two important measures, their amplitude and their wavelength. Amplitude, for light, means the intensity or brightness of the light, and wavelength dictates the color. Sound has similar attributes—amplitude and frequency (the inverse of wavelength). Both of these physical attributes maps onto a perceptual attribute. Amplitude maps onto loudness, frequency maps onto pitch. Here we consider pure tones, that is, sound waves in which air pressure changes follow the basic sine wave format. A pure tone is heard at a particular pitch but does not have the complexity you would expect when hearing a musical instrument (or a voice) play (or sing) that particular pitch.

In this illustration, you can manipulate the frequency and the amplitude of a sound to see how it changes our perception of a sound.