• Background
  • Instructions
  • Illustration
  • Quiz


The energy in any sound wave will weaken across time and space. Your clap may sound very loud to you because you are so close to it. But to your friend in another room, it will be audible but not loud. By the time the sound wave gets through the door and out into the street, the energy may have dropped off so much that a person walking by on the sidewalk may not hear it at all.

In this activity, you can play a click and observe how the sound energy dissipates as it travels from where the sound starts.


Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab


Below is a list of the ways that you can alter the illustration. The settings include the following:

Sound Intensity: adjust the intensity of the sound. Louder sounds will travel farther.
X Position of Sound Source: move the brown dot horizontally to change where the sound begins.
Y Position of Sound Source: move the brown dot vertically to change where the sound begins.
Number of Molecules: choose the number of air molecules to simulate.


Pressing this button restores the settings to their default values.