Hearing - Function of Ear

Ear performs two quite different functions. 
  1. detect sounds by receiving vibrations
  2. responsible for balance and sensing acceleration. 
 Ear has three divisions: 
   1. outer ear,  
   2.middle ear and   
   3. inner ear.                  
 Function of ear - to receive vibrations from the air and turn these signals into nerve             impulses that the brain can recognize as sounds
 Outer Ear -The outer part of the ear directs sounds down the auditory canal, and on to       the eardrum. The sound waves will cause the eardrum to vibrate.
 Middle Ear -Beyond the eardrum is the middle ear which transmits vibrations from the eardrum by way of three small bones known as the ossicles, to the fluid of the inner ear.  The middle ear also contains two muscles which help to protect the ear from sounds
above 80 dB by means of the acoustic or aural reflex, reducing the noise level by up
to 20 dB.
Eustachian tube - middle ear is usually filled with air which is refreshed by way of the eustachian tube which connects this part of the ear with the back of the nose and mouth. This tube can allow mucus to travel to the middle ear which can build up, interfering with normal hearing
Inner Ear - is filled with fluid. The last of the ossicles in the middle ear is connected to the cochlea. 
Cochlea contains a fine membrane (the basilar membrane) covered in hair-like cells which are sensitive to movement in the fluid.
 Any vibrations Cochlea detect cause neural impulses to be transmitted to the brain via the auditory nerve.
Performance and Limitations of Ear -  is associated with the range of sounds that can be heard - both in terms of  pitch (frequency) and volume of the sound.
Audible frequency range - between 20 and  20,000  cycles/second (or Hertz), with greatest sensitivity at about 3000 Hz.                                                                                              Volume (or intensity) of sound is measured in decibels (dB).
Impact of Noise on Performance - Noise can have various negative effects. 
• be annoying (e.g. sudden sounds, constant loud sound, etc.);
• interfere with verbal communication between individuals in the workplace;
• cause accidents by masking warning signals  lor messages;
• be fatiguing and affect concentration, decision making, etc.;
• damage  hearing (either temporarily or permanently).

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