Many consider that the person hears ears. Actually an ear of people only perceives sounds. He hears by means of an organ of hearing which is rather difficult arranged. The ear is only one of its parts.
For perception of sounds at person answers the body called an ear. Outside the external ear which turns into acoustical pass and comes to an end with an eardrum is located. It divides an external and middle ear. The stone which is called a hammer is attached to this membrane. By means of two other stones (anvil and a stirrup) this hammer transfers vibration of an eardrum further, to the membrane twirled in the form of a snail – an inner ear. It is a tube with liquid inside. Air fluctuations very weak that could shake directly the liquid which is there. Therefore an eardrum together with membranes of a middle and inner ear, make the hydraulic amplifier. The sizes of an eardrum there is more membrane of an inner ear therefore pressure increases ten times. In an inner ear there is a webby channel too filled with liquid. On its lower wall the receptor device of the acoustic analyzer which is covered with hair cells is located. These cages can catch fluctuations of the liquid filling the channel. Each such cage catches a certain sound frequency and will transform to electric impulses. Then these impulses on an acoustical nerve are transferred in a brain. The acoustical nerve consists of thousands of thin nervous fibers. Each fiber begins from a certain place of a snail and transfers a certain frequency. Low-frequency sounds are transmitted on the fibers proceeding from top of a snail, and high-frequency on the fibers connected with her basis. Thus, different sounds cause electric excitement of the different fibers which are in structure of an acoustical nerve. The brain can perceive and interpret these distinctions. Two ears are necessary to the person to define the direction on a sound source.