Noise levels around the Schiphol airport: Difference between revisions

Revision as of 11:16, 15 March 2007

Scope
Noise levels describes the noise levels around the Schiphol airport in the Netherlands.

Description

Above certain noise levels (if it is too quiet measurement can become inaccurate), the noise levels on the ground from aircraft operations can be measured using carefully sited, purpose designed microphones. This is particularly useful to measure how an aircraft is being flown. Because of the effects of factors such as ambient noise and weather, individual measurements only give a snapshot assessment and do not always reflect the average situation. For this reason measurement is most often used in assessing operational performance rather than overall noise impact. To reach an understanding of average noise levels, noise is usually modelled using computer programmes that simulate aircraft “virtually” following an airports operating procedures, but with suitable variability such as track dispersion to make it more realistic. These models, such as the widely used “International Noise Model”, produce aircraft noise footprints for the number of and type of aircraft using an airport in order to calculate the extent of particular noise levels around the airport. This will assume average weather conditions. These noise “contours” can then be placed on a map to see which communities are subjected to different degrees of average noise levels. But it should be remembered that, as average conditions rarely occur, the noise contours are only indicative of typical noise impact. [1]

The different units used to measure noise levels

The most widely used unit for measuring noise levels is dB(A) - the A-weighted scale in decibels. This unit attempts to reflect human reaction to "loudness". The human ear's response to sound relates to sound pressure in a way that is approximately logarithmic. This means that a significant reduction in noise activity results in a comparatively small reduction in the noise heard by the human ear.

Other dB based measurement units are uniquely related to aircraft.

The perceived noise (PNdB) and effective perceived noise (EPNdB) scales incorporate the different frequencies and duration of noise patterns, resulting from various speeds and modes of operation of aircraft. There is no agreement, even amongst the experts, on which measurement is the most representative, or the most relevant in a particular situation. However, the International Civil Aviation Organisation (ICAO) uses EPNdB for expressing its noise certification standards; Maximum Sound Level (LAmax) is the maximum instantaneous value recorded; Equivalent continuous sound pressure (Leq) is a measure of the average sound pressure level during a period of time.

The European Community proposes “Lden” as the common unit for measuring transport noise. Day-evening-night level (Lden) is based on Leq over a whole day with a penalty of 10 dB(A) for night time noise (22.00-7.00) and an additional penalty of 5 dB(A) for evening noise (i.e. 19.00-23.00).

References

reference 1

Definition

Causality

List of parents:

Noise emissions

Data

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 == Description ==
+Above certain noise levels (if it is too quiet measurement can become inaccurate), the noise levels on the ground from aircraft operations can be measured using carefully sited, purpose designed microphones. This is particularly useful to measure how an aircraft is being flown. Because of the effects of factors such as ambient noise and weather, individual measurements only give a snapshot assessment and do not always reflect the average situation. For this reason measurement is most often used in assessing operational performance rather than overall noise impact. To reach an understanding of average noise levels, noise is usually modelled using computer programmes that simulate aircraft “virtually” following an airports operating procedures, but with suitable variability such as track dispersion to make it more realistic. These models, such as the widely used “International Noise Model”, produce aircraft noise footprints for the number of and type of aircraft using an airport in order to calculate the extent of particular noise levels around the airport. This will assume average weather conditions. These noise “contours” can then be placed on a map to see which communities are subjected to different degrees of average noise levels. But it should be remembered that, as average conditions rarely occur, the noise contours are only indicative of typical noise impact. [http://www.eurocontrol.int/environment/public/standard_page/noise.html]
+'''The different units used to measure noise levels'''
+The most widely used unit for measuring noise levels is dB(A) - the A-weighted scale in decibels. This unit attempts to reflect human reaction to "loudness". The human ear's response to sound relates to sound pressure in a way that is approximately logarithmic. This means that a significant reduction in noise activity results in a comparatively small reduction in the noise heard by the human ear.
+Other dB based measurement units are uniquely related to aircraft.
+The perceived noise (PNdB) and effective perceived noise (EPNdB) scales incorporate the different frequencies and duration of noise patterns, resulting from various speeds and modes of operation of aircraft. There is no agreement, even amongst the experts, on which measurement is the most representative, or the most relevant in a particular situation. However, the International Civil Aviation Organisation (ICAO) uses EPNdB for expressing its noise certification standards; Maximum Sound Level (LAmax) is the maximum instantaneous value recorded; Equivalent continuous sound pressure (Leq) is a measure of the average sound pressure level during a period of time.
+The European Community proposes “Lden” as the common unit for measuring transport noise. Day-evening-night level (Lden) is based on Leq over a whole day with a penalty of 10 dB(A) for night time noise (22.00-7.00) and an additional penalty of 5 dB(A) for evening noise (i.e. 19.00-23.00).
 === References ===