These sites will visualize, what happens with waves, modes, standing waves and much more. At least easier to grasp than complex formula.
A smalll collection of acoustics-related animations
A. John Mallinckrodt Professor of Physics, Cal Poly Pomona. The following are links to pages containing animations I have put together in support of various courses. The list is pitifully small at this time, but it will grow. All movies and animated gifs were produced and directed by A. J. Mallinckrodt who could not have made them without the steadfast loving support of his computer algebra package, Maple.
http://www.csupomona.edu/%7Eajm/materia ... tions.html
Acoustics and Vibration Animations
Contains animations which visualize certain concepts concerning acoustics and vibration. The choice of animations coincides with topics covered in the courses of Dan Russell, Ph.D., Associate Professor of Applied Physics at Kettering University in Flint, MI
Animations for Acoustics Education
These animations are freely available for learning about acoustics. Anyone teaching acoustics is particularly welcome to use them in their classes. It is also OK to use them any other way you want, except that you may not charge anyone money for them or sell them in any way, either individually or as components of a larger package. They are free. All of these movies are in Apple's QuickTime format. QuickTime is freely available for both Macs and Windows based machines, if you don't already have it. A common QuickTime player for Unix machines is called "xanim".
Let's study about waves
Not many animations, but the ones that are there, are a nice piece of programming. This are Java applets.
http://www2.biglobe.ne.jp/~norimari/sci ... JavaP.html
Simulations of Doppler effect
You can get some QuickTime movies of Doppler effect here. These movies are calculated with Mathematica on Macintosh
http://www2.biglobe.ne.jp/~norimari/sci ... ppler.html
Simulations of two-source interference pattern
You can get some QuickTime movies of two-sorce interference pattern here. These movies were calculated with Mathematica and flattened.
http://www2.biglobe.ne.jp/~norimari/sci ... /e-if.html