Noise pollution is the disturbing or excessive noise that may harm the activity or balance of human or animal life. The source of most outdoor noise worldwide is mainly caused by machines and transportation systems, motor vehicles, aircraft, and trains. Outdoor noise is summarized by the word environmental noise. Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential areas.
Indoor noise is caused by machines, building activities, music performances, and especially in some workplaces. There is no great difference whether noise-induced hearing loss is brought about by outside (e.g. trains) or inside (e.g. music) noise.
Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972, other local and state governments passed further regulations.
A noise regulation restricts the amount of noise, the duration of noise and the source of noise. It usually places restrictions for certain times of the day.
Image noise is random (not present in the object imaged) variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the sensor and circuitry of a scanner or digital camera. Image noise can also originate in film grain and in the unavoidable shot noise of an ideal photon detector. Image noise is an undesirable by-product of image capture that adds spurious and extraneous information.
The original meaning of "noise" was and remains "unwanted signal"; unwanted electrical fluctuations in signals received by AM radios caused audible acoustic noise ("static"). By analogy unwanted electrical fluctuations themselves came to be known as "noise". Image noise is, of course, inaudible.
Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of analog as well as digitized signals, representing time-varying or spatially varying physical quantities. Signals of interest can include sound, electromagnetic radiation, images, and sensor readings, for example biological measurements such as electrocardiograms, control system signals, telecommunication transmission signals, and many others.
A police officer (also known as a policeman/woman, police agent, patrolman, cop, and constable in some forces, particularly in the United Kingdom and other Commonwealth nations) is a warranted employee of a police force. In the United States, "officer" is the formal name of the lowest police rank. In many other countries, "officer" is a generic term not specifying a particular rank, and the lowest rank is often "constable". In many other countries there is no such title as "police officer", as the use of the rank "officer" is legally reserved for military personnel only and thus not applicable. Police officers are generally charged with the apprehension of criminals and the prevention and detection of crime, and the maintenance of public order. Police officers may be sworn to an oath, and have the power to arrest people and detain them for a limited time, along with other duties and powers.
Some police officers may also be trained in special duties, such as counter-terrorism, surveillance, child protection, VIP protection, and investigation techniques into major crime, including fraud, rape, murder and drug trafficking.