This very detailed and well-thought out set of online activities gives users the opportunity to listen closely to the particular sounds of the natural world. Based at the Exploratorium in San Francisco, this site was sponsored by the National Science Foundation and the National Endowment for the Arts. The site is divided into three sections: “At the Museum”, “Listening Guides”, and “Online...

The Music Acoustics Web site is maintained by the University of New South Wales School of Physics. General topics covered include what a decibel is, what interference beats are, what a sound spectrum is, what acoustic impedance is, and others. Specific instrument questions are also answered, such as waves in strings, flute and clarinet acoustics, Helmholz resonance, and pipes and harmonics. This...