
One of the more interesting scientific qualities of both sound and light is
known as of coherent .vs. incoherence. In the natural world almost all sensory
information is perceived contains mixed frequencies. For instance sunlight is made of light
frequencies of all colors and is therefore called incoherent light. In 1960
Theodore Mainman demonstrated the first true coherent light source. The laser outputs
light of the coherent type in that the light waves are of the same frequency and
are all in phase.
Sound is a longitudinal, mechanical wave that must travel though a medium,
like air or water. It cannot travel through a vacuum. There is no sound in outer
space. Sound is made by producing a variation in pressure in the medium. A
region of increased pressure on a sound wave is called a
compression (or condensation). A region of decreased pressure on a sound
wave is called a rarefaction (or dilation).

COHERENT SOUND ?
There is no "official scientific" designation for coherent sound, but let's
look at the same unusual phenomenon in sound. In the natural world, sounds we normally encounter
all almost all
incoherent, and sometimes chaotic. Sounds from individual tuning forks or glass
bowls generate a single coherent frequency wave but the impact on human .
And then there is the human response to music.
Sacred Sound
The difference between normal sounds and sacred sounds has been prooven to be similar to the phenomenon of incoherent and coherent sound respectively.