
Dick Dale's surf guitar is strapped to his side and
plugged in. Beach Boys harmonies drift with the breeze
from a cheap portable radio as an endless cascade of Pacific
waves pound an expansive warm and sandy California
beach. Then a stranger from Mars or the US Congress
asks, "What is an ocean wave?"
Try this -- An ocean wave is energy transmitted in a
spring-like motion through the water. It initiates with
an energy disturbance that causes water molecules to squeeze
(compress) and then expand (rarefact) into neighboring water
molecules, which repeat the compress/rarefact action.
This compression rarefaction cycle continues until the wave
terminates on the beach.
Surfs Up
For many in California and
Hawaiian beach communities, the surf report is more meaningful
than a traditional weather report. For their sake, let's
construct an assessment of the consistency, the power, and the
length of the rides they can expect.
For example, the length of the ride, or wavelength, can be
described as the distance traveled by one wave cycle.
The cycle begins at a wave's crest, continues to its bottom,
then up to the next wave crest. The consistency or
frequency of the waves can be expressed by how many cycles
occur per hour, per minute.
Objectively gauge the power of the wave by its height, or
amplitude, at the crest of each cycle. However the
backdrop of a vast horizon in an expansive ocean can distort
the perceived-height of the wave and mask its real objective
power. Therefore, offer a multiplier of the
objective-power that expresses the waves perceived or
subjective intensity.
But what does this have to do with
audio or video?
All energy, such as the
acoustical-energy of sound, and the electromagnetic energy of
visible light and radio, is a wave that can be described by
its
wavelength,
frequency,
amplitude,
and when-applicable, its
subjective intensity.
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