Chapter 2 INTRODUCTION TO NOISE
2.1 SOUND: Sound is a form of energy that produces a sensation of hearing in our ears. Sound is produced by vibrating objects. The matter or substance through which sound is transmitted is called a medium. It can be solid, liquid or gas. Sound moves through the medium form the point of generation to the listener. When an object vibrates, it sets the molecules of medium around it vibrating. The molecules do not travel all the way from the vibrating object to the ear. A molecule of the medium in contact with the vibrating object is first displaced from its equilibrium position. It then exerts a force on the adjacent molecule. As a result of which …show more content…
The sound generation mechanisms of machinery are reasonably well understood and do not vary much under normal working conditions of an industry. Reduction in industrial noise may be achieved by encouraging quieter equipment or by zoning of land into industrial and residential areas. 2.4.2 Transportation noise:
It is the main source of environmental noise pollution. Transportation noise is mainly derived from Road traffic, Rail traffic and Air traffic. As a general rule, larger and heavier vehicles emit more noise than smaller and lighter vehicles.
The noise of road vehicles is mainly generated from the engine and from frictional contact between the vehicle and the ground and air. Railway noise depends primarily on speed of the train but variations can be there depending upon the type of locomotives, wagons and rails. Aircraft generates highest levels of noise amongst all transportation modes. Aircrafts takeoffs produce intense noise from jet engine as well as vibration and
2.1 SOUND: Sound is a form of energy that produces a sensation of hearing in our ears. Sound is produced by vibrating objects. The matter or substance through which sound is transmitted is called a medium. It can be solid, liquid or gas. Sound moves through the medium form the point of generation to the listener. When an object vibrates, it sets the molecules of medium around it vibrating. The molecules do not travel all the way from the vibrating object to the ear. A molecule of the medium in contact with the vibrating object is first displaced from its equilibrium position. It then exerts a force on the adjacent molecule. As a result of which …show more content…
The sound generation mechanisms of machinery are reasonably well understood and do not vary much under normal working conditions of an industry. Reduction in industrial noise may be achieved by encouraging quieter equipment or by zoning of land into industrial and residential areas. 2.4.2 Transportation noise:
It is the main source of environmental noise pollution. Transportation noise is mainly derived from Road traffic, Rail traffic and Air traffic. As a general rule, larger and heavier vehicles emit more noise than smaller and lighter vehicles.
The noise of road vehicles is mainly generated from the engine and from frictional contact between the vehicle and the ground and air. Railway noise depends primarily on speed of the train but variations can be there depending upon the type of locomotives, wagons and rails. Aircraft generates highest levels of noise amongst all transportation modes. Aircrafts takeoffs produce intense noise from jet engine as well as vibration and