I'm Looking to do a science fair project for my Science Research class and i came up with this idea where i would test if the frequency of sound would be affected by gases and liquids. Whats i would do is i would have some device playing sound on one end of a tube, have a material that sound goes through easily and then i have gas or liquids in there then i have that same material and then a receiver. ANYWAY to my main question, has anyone done this experiment and actually gotten some results about where frequency is altered by gas or liquids? if you could post below with some kind of source so i know i can do this experiment and not have it a dud.