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A l l About Ears.

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What Exactly is Sound?

Sound is defined as a mechanical wave

that propagates through a medium via

local regions of compressions andrarefactions, stemming from the kinetic

energy of a sound source. Particles in the

medium are displaced by the wave andoscillate.

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Compressions are regions of increased particle

density.

Rarefactions are regions of decreased particle

density.

Compressions and Rarefactions.Sound moves by displacing molecules in the air, creating

high, and low pressure pockets (Compressions and

Rarefactions, respectively). Sound pressure is measured

in Pascals (Pa).

Perceived loudness correlates roughly logarithmically to

its sound pressure.

Sound Pressure.

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Common Factors Operating Upon A Sound Before Hitting Your Ear

Echoes A reflection off of a hard

surface. A true echo is awave that has been

reflected by an obstructionin the medium.

Reverberation A buildup of reflections in a

space that persists afterthe original sound has

passed. Differs fromechoes based on theamount of reflected sound.

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The Doppler Effect: An

apparent change in

frequency and

wavelength perceived bya moving observer in

relation to the sound

waves. The sounds pitch

is higher as it

approaches, and lower as

it recedes from the

listener.

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How Do Ears Work?

While your sense of smell, taste and vision

all involve chemical reactions, but your

auditory system is based solely onmechanical, physical movements. (1)

Artificial additives to sound waves such as

reverb, echoes, and the Doppler effect alloccurbefore hitting the ear.

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Anatomy of the Human Ear

The ear consists of: The outer ear, the middle ear, and the inner ear.

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The Outer Ear The outer ear consists of:

The Pinna

The Ear Canal

The Eardrum

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The Pinna

The Pinna collects sound, acting

as as a funnel to amplify sound

and directing sound toward the

ear canal.

In addition, the pinna doubles by

adding directional information to

the sound (thus the inherent

ability to know which direction asound is coming from.)

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The Ear CanalThe ear canal is a tube

running from the pinna to the

eardrum, roughly 26 mm long

and 7 mm in diameter.

The outer edge of the ear

canal contains hair and waxto help prevent harmful items

from entering the ear canal.

Acoustically, the ear canal

provides 10 dB of boost to

the frequencies 2,000-4,000Hz. Because of the sensitivity

of the ear canal to this range,

prolonged exposure of high

intensity can lead to hearing

damage.