Variation n. varying, departure from a former or normal condition or action or amount or from a standard or type, extent of thisvariance n. disagreement, difference of opinion, dispute, lack of harmony. A single speaker loses level over distance at the free-field rate in all directions. Range ratio can also be reduced by partitioning the coverage. The term spectral variance applies either way, because all the variance forms are "over the space". Astronomers use "red shift" as a range finder for distant sources of light in the universe. Proportional beamwidth is preferred for large quantities in highly overlapped arrays. The forward sonic image variance, a natural aspect of sound transmission. Our horizontal localization perception mechanism is much more sensitive than the vertical. Ripple variance progression runs in parallel for multiple reflections, and their added effects are level proportional. Speaker coverage patterns have limited variability in shape but are highly variable over frequency.