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Humans have depended on their sence of hearing for millions of years. It
is the way that humans receive their main way of communication: sound.
Hearing is what people depend on to help them communicate with others, locate
certain objects, like the phone, and many other things. We have made great
steps in improving and preserving human hearing, but to understand underwater
hearing you must understand how hearing itself works.

In humans and other mammals, the auditory receptors are found in the inner
ear and the whole structure for hearing consists of the outer ear, the middle
ear and the inner ear.
The outer ear consists of three important components, the pinna or the ear
itself, the auditory canal and the tympanum or the eardrum. Most mammals are
able to move their pinna in order to pick up the source of the sound and to
maximize the sound input.
The middle ear consists of mainly bones, the three important bones, the
malleus, incus and the stapes. These three bones are also known as the
hammer, anvil and stirrup respectively due to their functions. Acting
together as a jointed lever, these bones transfer the vibrations of the
eardrum to a thin membrane in the inner ear.
The inner ear consists of the cochlea, which is the lengthy fluid-filled
tube, which is coiled like a snail shell, and the vestibular apparatus. The
cochlea is U-shaped and contains sensory neurones involved in hearing. At one
end of the cochlea is an oval window to which the stapes is affixed while the
other end contains the round window.
Sound striking the eardrum is transferred by the bones in the middle ear unto
the oval window of the cochlea, causing the fluid in the cochlea to vibrate.
In the middle of the cochlea is the organ or Corti. Auditory receptors are
found in this organ which converts the vibrations in the fluid of the cochlea
into impulses which are then transmitted by the auditory nerve to the brain
where the impulses are interpreted.

Now that we know how the human ear works above water lets take a look at how
it works below water.

There are two ways of hearing: air conductivity and air conductivity.
Underwater, humans use bone conductivity because there is no air in the
water, so the ear cannot pick up sound waves because eit has water in it,
thus air conductivity is useless underwater. This means that humans hear
underwater through vibrations in the bones. Through bone conductivity, humans
can pick up sounds of greater tonality underwater than above water. This
means that above water, humans can pick up sounds with a lower tonality, more
easily.

 

KEY

Blue Information = Written by Daniel and Ike

Red Information = Taken from: http://library.thinkquest.org/28457/hear.shtml

 

Black Information = Take from Hannnah and Elizabeth's project

 The sound diagrams were taken from :

http://www.neurophys.wisc.edu/h&b/auditory/anatomy/a03.html

The ear picture was taken from:

http://www.entnet.org/healthinfo/ears/ear.cfm

 

This background was taken from: WWW.nepthys.com/textures/texurestation_blue.htm