21st Century Hearing Medical Information
The
Ear [also see: products and product range]
The ear responds to the vibrations that constitute sound,
and these are translated into nerve signals and passed
to the brain. The ear consists of three parts: outer ear,
middle ear, and inner ear. The outer ear is a funnel that
collects sound, directing it down a tube to the ear drum
(tympanic membrane), which separates the outer and middle
ear.
Sounds
vibrate this membrane, the mechanical movement of which
is transferred to a smaller membrane leading to the inner
ear by three small bones, the auditory ossicles. Vibrations
of the inner ear membrane move fluid contained in the
snail-shaped cochlea, which vibrates hair cells that stimulate
the auditory nerve connected to the brain. Three fluid-filled
canals of the inner ear detect changes of position; this
mechanism, with other sensory inputs, is responsible for
the sense of balance.
When
a loud noise occurs, muscles behind the eardrum contract
automatically, suppressing the noise to enhance perception
of sound and prevent injury. Below you can see a sectional
view of the ear and a modern hearing aid.
Sound
A physiological sensation received by the ear, originating in a vibration that communicates itself as a pressure variation in the air and travels in every direction, spreading out as an expanding sphere.
| All sound waves in air travel with a speed dependent on the temperature; under ordinary conditions, this is about 330 m/1,070 ft per second. The pitch of the sound depends on the number of vibrations imposed on the air per second, but the speed is unaffected. The loudness of a sound is dependent primarily on the amplitude of the vibration of the air. The lowest note audible to a human being has a frequency of about 20 hertz (vibrations per second), and the highest one of about 20,000 Hz; the lower limit of this range varies little with the person's age, but the upper range falls steadily from adolescence onwards. |
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For further information about the ear and how its functionality can be enhanced
contact 21st Century Hearing |
