Noise pollution

Noise is defined as sound that is disruptive or annoying, or that has harmful effects on human health. Its negative effects on the organism can be manifested specifically as a malfunction of the hearing apparatus, or they can cause functional changes such as the degree of fatigue, sleep depth disorder, blood pressure etc. The noise burden of our population is about 40% caused by noise from the work environment and 60% by noise from the non-work environment.

Among the main sources of noise we rank

 * 1) 	Traffic noise – automobile, rail and air traffic.
 * 2) 	Noise in the working environment – ​​hand mechanized tools (chainsaws, pneumatic hammers, etc.), mining machinery, metallurgy, engineering (machine tools), textile industry (looms), air conditioning equipment, mobile equipment, agriculture, forestry...
 * 3) 	Noise related to housing – built-in technical equipment of the house (elevators, transformers, boiler rooms), sanitary and technical equipment of the house (bathrooms, toilets), activities of people in the apartment (talk, radio, TV, vacuum cleaner, kitchen appliances, dishwashers, washing machines, etc.).
 * 4) 	Noise related to spending free time – cultural and social facilities (theatres, cinemas, concert halls, pilgrimages, etc.), sports facilities (e.g. playgrounds, swimming pools, shooting ranges), individual reproduction and listening to music (players with speakers or headphones).

Basic quantities
Sound is characterized by acoustic pressure, unit is pascal [Pa, or N × m-2] and frequency, unit is hertz [Hz]. Since the energy or sound intensity is proportional to the square of the sound pressure (p 2 ) and the human ear can distinguish changes in sound intensity up to 14 orders of magnitude, the quantity  level (sound intensity) L [dB] (decibel) was introduced. The level is given by the logarithmic ratio of the measured and reference sound pressure.

2 · 10 −5 Pa, i.e. the value of the acoustic pressure that causes a threshold hearing sensation in a normal, healthy, young human ear at a frequency of 1 kHz. The range of common sound pressure levels is from 0 dB to 140 dB. Frequencies range from 16 to 20,000 Hz. And the human ear is most sensitive at a frequency from 1 to 4 kHz. However, the human ear is not equally sensitive at different frequencies. Hearing sensitivity decreases towards the extreme audible frequencies.

Related Articles

 * Volume
 * Hearing threshold and auditory field
 * Audiometry (Physiology)