HOW WE HEAR
The auditory system is a complex and remarkable one. We don’t actually hear with our ears. They are a medium or method of transportation the sounds that are perceived, up to the brain to decipher. Sounds are collected in the form of sound waves or vibrations by the outer ear and funnelled along the ear canal. The human ear has the only skin lined cul-de-sac in the body,where at the end of the cul-de-sac is the eardrum. Like a drum that we would beat to make music, it is a tight thin membrane of skin and if perforated will alter or reduce the volume of sound.
The eardrum is connected directly to the three smallest bones in the body, commonly known as the hammer, anvil and stirrup. By the very nature and position of the bones, an increase in volume of up to 30% is applied to the incoming sounds. The last bone in the chain, the stirrup rocks over an opening (oval window) to the cochlea or hearing organ. Inside the cochlea there are around 30,000 microscopic hair like cells and two fluids called endolymph and per0lymph. These fluids in their make up are a little bit like the + and – minus of a battery in such that when these two fluids meet each other, they create an electro-chemical impulse. It is this impulse that is then fired up the hearing (auditory) nerve to the brain, the left side sends sounds to the right side of the brain and vice versa.
The brain works like a computor by translating the impulses received into the sounds that we hear. In most cases the damage caused by noise,hereditary or the aging process or presbycusis predominantly affects the higher pitched sounds first, due to the positioning of the hair like cells. The damage is not only permanent but is also progressive in such that it worsens year on year.
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