WE HEAR SOUND THROUGH EARS

WE HEAR SOUND THROUGH EARS

The shape of the outer part of the ear is like a funnel. When sound enters it, it travels down a canal at the end of which there is a thin stretched membrane. It is called the eardrum. It performs an important function. To understand what the eardrum does, let us build a tin-can model of the eardrum.

Activity 13.10: ( understanding the action of eardrum )

*  Take a plastic or tin-can. Cut its ends.

*  Stretch a piece of rubber balloon across one end of the can and fasten it with a rubber band.

*  Put four or five grains of dry cereal on the stretched rubber.

*  Now ask your friend to speak “Hurrey, Hurrey” from the open end (Fig.13.15).

*  Observe what happens to the grain.

*  Why do the grains jump up and down?

Figure 13.15: Understanding action of eardrum

The eardrum is like a stretched rubber sheet. Sound vibrations make the eardrum vibrate (Fig. 13.16). The eardrum sends vibrations to the inner ear. From there, the signal goes to the brain. That is how we hear.

Figure 13.16: Human ear

We must NEVER put a sharp, pointed or hard thing into our ear. It can damage the eardrum. The damaged eardrum can impair hearing.

Source: This topic is taken from NCERT TEXTBOOK