8th Class Science Sound Human Ears

       Human Ears

Ear is a sense organ that helps in hearing the sound. The human ear is divided into three parts:

(i) Outer ear

(ii) Middle ear

(iii) Inner ear

The outer ear consists of pinna. It collects the sound from the outer surroundings and transfers it to the middle ear, through the ear canal. At the end of the ear canal there is a thin elastic membrane, called eardrum. The middle ear consists of three bones/hammer/ anvil and stirrup. The inner ear contains a coiled tube called cochlea. Cochlea is filled with a liquid that contains nerve cell, which is sensitive to the sound. They are connected with the auditory nerves that transmits the message to the brain.

The sound wave coming from the outer surrounding is collected by the outer ear, called pinna. These sound waves are then pass on to the middle ear through the ear canal, which then fall on the eardrum. The eardrum starts vibrating rapidly, in turn causing the three bones to vibrates. The three bones amplify the sound from outer ear to several times and then pass it on to the inner ear. This cause the liquid in the cochlea to vibrate, and sets up the electrical impulse in the nerve cell. The electrical impulse is then carried by auditory nerves to the brain. The brain interprets these impulses as sound, and we get the sensation of hearing.

       The sound from the surrounding entering into our ear are collected by pinna. The sound which enters into our ear is not of high amplitude. They are amplified inside our ear. The part of the ear which does this work is?

(a) Ear Drum

(b) Hammer, Anvil and Stirrup

(c) Ear Canal

(d) Cochlea

(e) None of these

Answer: (b)

Explanation

The middle part of the ear amplifies the sound and it consists of three bones, hammer, anvil, and stirrup.

     The sound from our ear is carried to our brain, where it is interpreted and we are able to hear and identify the sounds. Which part of the ear carries the sound message to the brain?

(a) Optic Nerve

(b) Sensory Nerve

(c) Motor Nerve

(d) Auditory Nerve

(e) None of these

Answer: (d)

Explanation

The part of ear that carries the message from the ear to the brain is auditory nerve.