The Organ Of Hearing
The ear has two major functions, which are:
Hearing: detection of vibrations, their frequency (pitch) and amplitude (loudness).
Balance: detection of direction of motion, acceleration and head position related to gravity.
Ear Structure
- Pinna: This is said to collect sound waves and channel them into the external auditory canal.
- External Auditory Canal: Earwax and hairs prevent foreign material from entering the ear.
- Eardrum (tympanum): vibrates with the same frequency as the sound waves beating against it and it also separate the outer ear from the middle ear.
- Ear Ossicles (hammer, anvil, stirrup): transmit and amplify the vibrations of the eardrum to the inner ear.
- Eustachian Tube: When it opens, it equalizes the air pressure on both sides of the eardrum allowing the eardrum to vibrate freely so accurate sound sensations are generated.
- Oval Window: a flexible partition allowing transfer of vibrations to inner ear.
- Round Window: a flexible partition to deaden the pressure changes in the inner ear.
- Cochlea: conversion of sound waves into nerve impulses — ‘hearing’ apparatus.
- Auditory Nerve: carries impulses from the cochlea to the brain’s hearing centre.
- Semicircular Canals: detection of direction of motion and acceleration — balance.
- Utricle and Saccule: detection of acceleration and head position related to gravity — balance.
- Vestibular Nerve: carries impulses from the balance organs to the cerebellum.
Correction of a Hearing Defect
In children middle ear inflammation, called otitis media, is a common cause of hearing loss.
Cause: food allergy or bacterial infection.
Treatment: antibiotics or avoidance of the allergen.
Mechanism of Hearing
Sound waves are converted to nervous impulses in the following stages:
- r transmitted into the endolymph, from where it gets to organ of corti where nervous impulses are triggered off along the auditory nerve to the brain and back, and we are made to hear.
Mechanism of Balancing
Certain mechanisms are involved in the maintenance of balance. It all begins with the head. Head movement in any direction affects the fluid or endolymph in the corresponding semicircular canal which are at right angle to each other. This forces the sensory cells in the ampulla to set up impulses through the auditory nerve to the brain and intern for interpretation. The brain relays impulses to the body muscles for balancing or determining the position of the body.
How to take care of the ears
- Avoid loud noise
- Clean with cotton buds and avoid using sharp objects as it can damage the ear drum.
- Seek medical advice in case you suspect any infection.
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