In fact, shadows of sound waves exist. However in order to observe (hear) the effect the shadow casting object must be considerably larger than the wavelength of the sound.
Like light waves, sound waves can reflected, bent, refracted, diffracted and focused. Audible sound wavelengths are in the range of about 10 meters to about 2 centimeters, compared to less than one millionth of a meter for visible light.
LeeH
(published on 08/30/2009)
