"An acoustic levitator includes a pair of opposed sound sources which have interfering sound waves producing acoustic energy wells in which an object may be levitated. The phase of one sound source may be changed relative to the other in order to move the object along an axis between the sound sources."
Tom Danley also became interested in the Great Pyramid. Here is an extract from his interview in FATE magazine in 1998.
"In the Great Cheops Pyramid in the King's Chamber an F-sharp chord is resident, sometimes below the range of human hearing. Former NASA consultant Tom Danley feels the sound may be caused by wind blowing cross the ends of the air shafts and causing a pop-bottle effect. These vibrations, some ranging as low a 9 hertz down to 0.5 hertz, are enhanced by the dimensions of the Pyramid, as well as the King's Chamber and the sarcophagus case inside. According to Danley, even the type of stone was selected to enhance these vibrations."
In a 1997 video, JJ Hurtak said "this chord (F-sharp) is the harmonic of planet Earth to which native Americans still tune their instruments, and is in perfect harmony with the human body."
In the Great Pyramid these sounds are infrasonic vibrations, meaning they are below the level of human hearing.
Another researcher, John Reid, an acoustic engineer stated that while he was lying in the coffer and vocalizing various tones he was staggered by the intensity of the reflected energy. He said "the effect of lying in the sarcophagus while toning its prime resonant frequency is almost like taking a bath. Waves of sonic energy wash over your body almost like water".
It does not appear that all this was accidental or incorporated for a ritual. It must have had a more important purpose.
http://www.gizapyramid.com/articles/levitation.htm