EARS

Our ears provide us with two vital but very different senses : hearing
and balance. Sound detected by the ears provides essential information about
our external sourounding and allow us to communicate. In addition our ears
contribute to our sense of balance to maintain upright posture and move
without falling over.

Sound is the sensation produced by longitudinal vibrations in the
external environment. Loudness of sound is correlated with amplitude of sound
wave and pitch with frequency (No.of waves / unit time). Audible
frequencies to humans is in the range 20 – 20,000 cycles per second (cps,
Hz). Only the young people are able to hear this full range.
Sound perception depends on the loudness as well as frequency.

The human ear is most sensitive to 50 – 5000 Hz range. But most sounds we
normally hear fall within 500 – 5000 Hz. Since the human ear can differentiate a wide range of sound energy (the loudest noise perceived is
approximately 1012 times more intense than the softest whisper) the decibel
(dB) scale is used to measure the intensity of sound.

Our ability to hear depends on a complex series of events that occur
in the ear. Sound waves in the air are transmitted as vibrations through a
series of structures to the receptor for hearing. The physical vibrations are
detected and converted into electrical signals. Nerves carry the electrical
signals to the brain where they are interpreted. The interpreted messages
allow us to perceive the subtleties of sounds such as speech and music.

EARS

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