3-Control Measures of Sound Pollution:

        Sound is transmitted from the source to the recipient through a medium. Therefore noise can be controlled by using three methods which are : decrease in the intensity of the source - inhibition of the medium - protection of the recipient (which is the ear).

a- Decreasing Sound Intensity of the source:

        This is achieved by lowering the frequency of sound. As an example we can use quieter machines, move airports, highway roads and factories away from inhabited places, and use less noisy alarms. Noise control in the responsibility of every citizen. Citizens who raise the volume of wireless or a television set or use the horn of their cars in an improper way are all contributing to noise pollution.

b- Inhibition of the Medium:

        Most sounds are transmitted through air in the form of waves. They are also transmitted through materials by vibration of the particles in the material in response to sound waves and so cause resonance. Therefore, if machines are placed on rubber bases, their noise and movement decrease. So sound absorbers, sound barriers and sound reflectors can all be used.

c- Protection of the Recipient:

        We protect ourselves automatically against noises by putting our hands over our ears. Protective covers can also be placed over the ears in order to decrease the sound intensity to 50 decibels, At this degree, the sound of an aero plane taking off is lowered to that of an electric mixer or a sweeping machine.