Explain the structure of ear ?

The ear is one of the five sensory organs of our body. It recognizes the sound waves from various sources. The following figure shows the structure of a human ear.

The human ear consists of three main parts known as the outer ear, middle ear, and inner ear. The following chart shows the various parts of the ear.

  • Eardrum is the intersection of the outer and the middle ear.

  • Oval window is the intersection of the middle and the inner ear.

The stirrup bone of the middle ear is the smallest bone in human body.

Functioning of human ear

The following table lists the functions of different parts of the human ear.

Ear part

Sub-part

Functioning

Outer ear

Pinna

Collects and sends the sound to the ear canal

Ear canal

Sound travels through it to reach the eardrum

Ear drum or tympanic membrane

A very sensitive membrane that vibrates in response to the sound

Middle ear

Middle ear bones

Transfers the sound energy to the cochlea

Eustachian tube

Connects the middle ear to the throat

Inner ear

Semi-circular canal

Sends messages to the brain for balancing

Cochlea

Sends sound messages in the form of electrical impulses to the brain

Auditory nerve

Conducts electrical messages to the brain when sound is heard

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We are able to hear with the help of an extremely sensitive device called the ear. It allows us to convert pressure variations in air with audible frequencies into electric signals that travel to the brain via the auditory nerve.

The outer ear is called ‘pinna’. It collects the sound from the surroundings. The collected sound passes through the auditory canal. At the end of the auditory canal there is a thin membrane called the ear drum or tympanic membrane. When a compression of the medium reaches the eardrum the pressure on the outside of the membrane increases and forces the eardrum inward. Similarly, the eardrum moves outward when a rarefaction reaches it. In this way the eardrum vibrates. The vibrations are amplified several times by three bones (the hammer, anvil and stirrup) in the middle ear. The middle ear transmits the amplified pressure variations received from the sound wave to the inner ear. In the inner ear, the pressure variations are turned into electrical signals by the cochlea. These electrical signals are sent to the brain via the auditory nerve, and the brain interprets them as sound.

Figure- (Sound)

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