Sound Waves
What are sound waves?
Waves are perturbations in space and time, which are often periodic (repetitive). Sound waves are waves that compress and expand the medium through which the waves propagate (such as air). On this page, you can find a photograph of what sound waves look like.
Sounds waves are longitudinal, compression waves. The sound you hear is the result of rapidly compressed and expanded air. Humans can detect air vibrations, sound, between these frequencies: 16 Hz and 16,000 Hz (kHz), known as our hearing range.
Physics Lab has an excellent webpage on the fundamentals of waves.
The University of Indiana has good explanations of the properties of sound waves.
Science of Music is a collection of online exhibits and tutorials from the San Francisco Exploratorium's Accidental Scientist project.
Are there sound waves in space?
There are sound waves that travel through the ionized gas in space but our ears would never hear this. Check out Tim Jacob's web page to find out more about how our ear hears sound waves. Most movies include sound when explosions occur in space but this is made up to make the movie more interesting. If you were really in space watching an explosion, you would hear nothing.
Most of the sound or music created from space data is not originally from sound waves in space. Rather the sound you hear comes from changing this data, or information, into an audio file that can be played through speakers on a computer or stereo. Changing the data into sound is known as sonification.
