Ed's AV Handbook.com
Home Theater & High fidelity Stereo Audio

Chapter Two
AV Physics

Page 4

Batting practice for the audio/video pro and a primer for the novice

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Did You Hear That?

          When waves crash on a beach they transmit acoustical energy in a spring-like
motion through the air that arrives in the ear as sound.   A crashing wave causes air molecules to compress and then rarefact into neighboring air molecules.  This compression rarefaction cycle continues until the sound waves terminate in the ear or fade away.

The Ear
          In route to the brain, the ear converts compressions and rarefactions of air molecules into neuron discharges.  The compressions/rarefactions enter at the pinna, the ear's directional encoder.  They proceed into
the auditory canal, the ear’s resonating acoustic amplifier.  At the exit of the auditory canal the 'resonations' beat on an acousticav solutions, av installation, best buy auburn, home theater, stereo audio barrier, the eardrum.

The resonating 'drum' mechanically links
with the hammer, anvil, and stirrup of the middle ear's next boundary, the oval window of the inner ear.  All of this mechanical action activates the fluid sack of the
inner ear
, the final chamber.

The compressions and rarefactions of the inner ear fluid stimulate hair-like nerve terminals in the inner ear sack. The shifting hair-like nerves of the inner ear generate neuron discharges that
finally convey signals to the brain that produce sound.

See the Waves Crash on the Beach

          Light transmits energy in a spring-like motion via a sea of electromagnetic energy into our eyes.   For example, initiating energy from the sun causes electromagnetic energy to compress and rarefact until the energy encounters the surface of the crashing waves.   The water absorbs/filters some of the energy but the remainder is reflected.  The reflected energy initiates another compression-rarefaction cycle that continues until the cycle terminates in our eyes as a visible wave on the beach.

The Eye
The eye converts electromagnetic light into neuron discharges.  Light enters at the window of the eye the pupil and cornea.  The light then encounters the focusing lens of av solutions, av installation, best buy auburn, home theater, stereo audiothe eye which directs the light to the energy transfer point of the eye, the retina.  The retina consists of light- sensitive antennas called cones and rods. The cones and rods stimulate the optic nerve which produce neuron discharges to the brain.

Review of the Wave
Cycles/Second = Hertz = Hz

Frequency describes the timbre of sound, color of light, or a radio broadcast frequency

Wavelength = Speed Frequency
Distance traveled by one cycle of the wave
Sound = 56.5ft to 0.678in
Light = 440nm to 770nm
Radio = fraction of an inch to several hundred yards

Amplitude of the wave = power
Volume in decibels
Brightness in lumen
Radio power in watts

Subjective Intensity
Subjective power of the wave
Loudness of sound
Luminance of light

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Ed's AV Handbook.com
Batting Practice for the AV Pro and a Primer for the Novice.
Copyright 2007 Txu1-598-288   Revised 2018