Sound

This topic explains that vibrating objects produce sound. When a highly stretched band is plucked. It vibrates and produces sound. When it stops vibrating, it does not produce any sound. This concept is explained with the help of activities.

In this topic, you will learn how humans produce sound. Keep your hand on your throat. Do you feel any vibrations? In humans, the sound is produced by the voice box or the larynx. When the lungs force air through the slit, the vocal cords vibrate.

This topic explains that sound needs a medium to travel. It may be solid, liquid or gas. When air has been removed completely from a vessel, then it is said that there is a vacuum in the vessel. Sound cannot travel through vacuum.

This topic describes how we hear sounds through our ears. The concept is explained with the help of a model eardrum.

This topic explains the amplitude, time period and frequency of a vibration. The to and fro motion of an object is known as vibration. The number of oscillations per second is called the frequency of oscillation.

We need a vibrating body to produce sound. This topic discusses that sounds of frequencies less than 20 vibrations per second and more than 20000 vibrations per second cannot be detected by human ear. Such sounds are called inaudible sounds.

This topic discusses noise and music. We hear different types of sounds around us. Some sounds are pleasant to our ears and make us feel comfortable, whereas other sounds are unpleasant to our ears and causes disturbance.

Excessive or unwanted sounds lead to noise pollution. Excessive noise in the surroundings may cause many health problems like lack of sleep, hypertension, anxiety, etc. The various measures to limit noise pollution are discussed in this topic.