INTRODUCTION TO SOUND
We hear many sounds around us. Some of them are very pleasant while some are not.
HOW SOUND IS PRODUCED?
Let us perform the following simple activities to investigate how sound is produced. Strike the bell with a hammer. Do you hear any sound? Touch the sounding bell with your finger. Do you feel vibrations produced in it? In all these such kind of activities, vibrations of bodies can be felt by touching their surfaces. These vibrations produce sound.
INTENSITY OF SOUND. Some sounds are very loud and some are very low. Sounds of whistle of a train, hammering of iron sheets, braying of donkey are some examples of loud sounds. On the other hand sounds of chirping of birds, rustling of leaves and ticking of clocks are low sounds. The loudness of a sound is called its intensity, & the louder the sound the higher is its intensity.
MEDIUM FOR SOUND TO TRAVEL. Although sound is produced by vibrations in a body but it reaches our ear through air. Does it also reach us through any medium other than air?
EXPLOSIONS IN THE CORE OF THE SUN. It is interesting to know that explosions in the core of the Sun are always taking place. The sound produced by them is extremely high. But we do not hear these sounds on the Earth. Can you tell its reason? Remember that there is vacuum between the Sun and the Earth.
NOISE. Many of the sounds which we hear in our every day life are not liked by us. For example, sound of auto rickshaw, sound of pressure horn of vehicles, sound of donkey or a dog and sound of jet aircrafts irritate us. Sounds which produce unpleasant effect are called NOISE. Musical sounds are the examples of other type of sound which do not irritate us. These are pleasant sounds. The musical or pleasant sounds are, in fact, collection of some continuous and regular sounds whereas noise is a collection of discontinuous, jerky and irregular sounds.
EFFECTS OF NOISE ON HUMAN HEALTH. Sounds producing noise affect our nerves and ears badly; Noise also disturbs the functions of our everyday life. Can you do your work with full attention and concentration at a noisy place? Noise affects our hearing, thinking and working abilities. Noise pollution affects the human health badly. People living in noisy areas often complain of headache. Noise can cause high Blood Pressure and may disturb our digestive system.
MEASURES TO REDUCE NOISE POLLUTION. When noise becomes unbearable, it is called noise pollution. Noise pollution from the environment could be reduced by the cooperation of both the Govt. and the Public. Although there are laws to reduce noise pollution in Pakistan but due to lack of knowledge most of the people do not care about them. Bus stands, airports and factories should be set up far away from the residential areas. Use of horn near hospitals, educational institutions and libraries should strictly be prohibited. We can also reduce noise pollution from the environment by ourselves. We should use good quality silencers in our vehicles and get them repaired in time. In addition to this we should keep the volume of T.V. or tape recorder low and avoid the use of loud speaker at high volume.