Question

Describe in detail the mechanism of hearing.

Answer 1

Mechanism of Hearing:

• The pinna collects sound waves & transmit the waves into the external auditory meatus. These waves strike to the tympanum, as a result, the tympanum begins to vibrate.


• The air imbalance caused in the middle ear due to vibrating tympanum is balanced by the air displaced through the eustachian tube.


• The ear ossicles convey the sound vibrations to the fenestra ovalis. They amplify the vibrations by 20 times.


• The pressure imbalance caused by the vibrating fenestra ovalis membrane is balanced by the membrane of fenestra rotunda.


• The vibrating membranes of the fenestra ovalis & fenestra rotunda cause the perilymph to vibrate which in turn makes the Reissner’s membrane to vibrate.


• The vibrating Reissner’s membrane causes the endolymph in the scala media to move. As a result, the tectorial membrane moves & strikes to the organ of Corti.
  Hence, the sound waves reach to the organ of Corti in the form of mechanical stimuli.


• The organ of Corti converts these mechanical stimuli into electromagnetic waves and transmits these waves to the cerebrum through the VIII cranial nerve.