คลื่นเสียง

1.http://th.wikipedia.org/wiki/%E0%B9%80%E0%B8%AA%E0%B8%B5%E0%B8%A2%E0%B8%87
http://www.mitrprasarn.com/index.php/2010-02-03-13-06-48/61-it-et-media/192-2010-03-08-06-23-31
http://www.thaigoodview.com/library/contest2551/science04/78/2/sound1/htmls/5.html
http://www.pt.ac.th/ptweb/prajead/sound/sound1.htm
http://www.icphysics.com/modules.php?name=Content&pa=showpage&pid=54