There is no specific frequency for stones that form behind the eyes due to oxalic acid poisoning, but 20.5 Hz is suppose to work for tonsil stones. To create such a beat, centered around 350 Hz for sharpening eyesight,
Tonsil Stones 20-5 Hz using sine 339-75 and 360-25 Hz
two frequencies 339.75 Hz (350-(20.5/2)=339.75) and 360.25 Hz (350+(20.5/2)=360.25) are used.
Good luck.
