Georgia State University
Georgia State University: Hyper Physics: Diffraction of Sound
This site's entry is a discussion of diffraction and its application to acoustics and acoustical design. Exceptional illustrations and great discussion throughout.
Other
S Cool Youth: Diffraction, Interference and Superposition
An interactive resource on diffraction, interference and superposition with descriptions, animations, and questions.
Science Struck
Science Struck: How Does Sound Travel?
Discusses the characteristics of sound waves and the conditions that affect the speed of sound.