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Physics of the ear and hearing

الكلية كلية طب حمورابي     القسم الكلية ذات القسم الواحد     المرحلة 1
أستاذ المادة نادية حسين صاحب طاهر       30/11/2018 14:48:17

Physics of the ear and hearing

Objectives

Mechanical principle of hearing process.
Physical aspect of ear and hearing.
Sensitivity of the ear.
Hearing loss (Deafness) and hearing aids

The sense of hearing involves
1. The mechanical system that stimulates hair cells in the cochlea.
2. The sensors that produce the action potentials in the auditory nerves.
3. The auditory cortex, the part of the brain that decodes and interprets the signals from the auditory nerves.

Deafness or hearing loss results if any of these parts malfunction. The ear is
a cleverly designed converter of very weak mechanical waves in air into electrical pulses in the auditory nerve

The outer ear
It aids in funneling sound waves into the canal, the external auditory canal besides storage place for ear wax serves to increase the sensitivity in the region of 300 - 4000 Hz, the canal is about 2.5 cm length.
Length = (? /4) and resonance frequency about (3300 Hz), ? = 10 cm
Consist of three bones called ossicles are full adult size. Before birth the fetus can hear while it is still in the womb. They transmit vibrations from eardrum to inner ear, the ossicles amplify pressure of sound waves to inner ear. The lever action amplify the force by a factor about 1.3, a much larger gain in pressure obtained by piston Action.

Eustachian tube is a canal that connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity.
It controls the pressure within the middle ear, making it equal with the air pressure outside the body. It is normally closed rather than open, serves to equalize pressure


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .