To Cathryn,

"In Japan, what is the distance used to calculate eartones re: earthquakes?"

I have yet to know of anyone in Japan who thinks eartone length is connected to distance. So there is no calculation that I know of.

The distance referred to is assumed to be fairly local, and the correlated quakes to be shallow quakes, rather than deep ones.

Many people here perceive a direction, and are looking at a local distance in a particular direction.

In the page Don linked, polarization is mentioned. I too think that is the explanation for perception on one side of the body.