[AntonioLao]

“Howling wind”, “murmuring fog”, “whispering breeze”, “echoing mountains”, and “thundering cloud” all seem to indicate the vocal ability of air. Although these are far from having semblance of melodic rhythms, proportional orders and pattern do exist. The audible sounds are not predominantly produced by self-interaction but mostly from interactions of air with matter within hollow cavities, from bouncing reflections off solid walls, or from colliding frictions among air molecules of different weights and sizes. All imply physical contact of lesser matter with greater matter.

The theory of sound suggests the orderly formation of longitudinal waves when matter interacts with matter. However, the waves could only move within a matter medium of much lesser density, weight, and size. On the other hand, if the matter medium is of comparable density, weight and size with the colliding matter then no propagating sound waves could ever be produced. Night or day would become as silent as the deep of inner space or the span of outer space.