Effective perceived noise in decibels (EPNdB) is a measure of the relative noisiness of an individual aircraft pass-by event. It is used for aircraft noise certification and applies to an individual aircraft, not the noise exposure from an airport. Separate ratings are stated for takeoff, overflight and landing events, and represent the integrated power sum of noisiness during the event. Instantaneous value of noisiness is computed with the PNL or PNdB metric over the period within which the noise from the aircraft is within 10 dB of the maximum noise (usually at the point of closest approach.) It is defined in Annex 16 of the

Convention on International Civil Aviation The Convention on International Civil Aviation, also known as the Chicago Convention, established the International Civil Aviation Organization (ICAO), a specialized agency of the United Nations charged with coordinating international air trav ...

and in Part 36 of the US

Federal Aviation Regulations The Federal Aviation Regulations (FARs) are rules prescribed by the Federal Aviation Administration (FAA) governing all aviation activities in the United States. The FARs comprise Title 14 of the Code of Federal Regulations (CFR). A wide variety o ...

. The scaling is such that the EPNdB rating represents the integrated noisiness over a ten-second period; EPNdB of 100 dB means that the event has the same integrated noisiness as a 100 PNdB sound lasting ten seconds. Direct comparison with A-weighted sound pressure level, which is used for many other environmental sound measurements, is not possible because PNdB is a noisiness metric rather than a sound pressure metric. It is important to make the distinction between loudness and noisiness. The same kinds of analytical methods are used but instead of using

equal-loudness contour An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon and i ...

s, equal-noisiness contours are derived and used instead. The EPNdB metric is only used in the US for aircraft certification purposes. In Australia and Canada, it's the basis for the ANEF and NEF noise exposure forecast used in place of the DNL and Day-evening-night metrics used in the US and Europe respectively.

Computation of EPNdB

Detailed information on measurement of aircraft

acoustic signature The term acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines. In addition, aircraft, machinery, and living animals can be described as having their own characteristic ...

to meet the requirements of Annex 16 is found in ICAO Document 9501 and IEC 61265. Data acquisition in one-third-octave bands is required, followed by processing to yield a logarithmically-scaled value in decibels relative to a sound pressure of 20 micropascals for each one-third-octave band. The individual band sound pressure levels are converted to "noy" valuesEnvironmental Technical Manual, Volume I. Procedures for the Noise Certification of Aircraft
(2012) International Civil Aviation Committee on Aviation Environmental Protection. which are then summed in the manner of Stevens' MKVI loudness to yield a total noy value. Noy is a linear unit of noisiness like

sone The sone () is a unit of loudness, the subjective perception of sound pressure. The study of perceived loudness is included in the topic of psychoacoustics and employs methods of psychophysics. Doubling the perceived loudness doubles the sone v ...

is for loudness, and is then converted into PNL or PNdB (the terms are interchangeable) which is a logarithmic unit like

phon The phon is a logarithmic unit of loudness level for tones and complex sounds. Loudness is measured in sone which is a linear unit. Human sensitivity to sound is variable across different frequencies; therefore, although two different tones may ...

which is the logarithmic unit for loudness. EPNdB is the integrated PNdB value over the duration of the pass-by event, normalized to a 10-second event duration using

Stevens's power law Stevens' power law is an empirical relationship in psychophysics between an increased intensity or strength in a physical stimulus and the perceived magnitude increase in the sensation created by the stimulus. It is often considered to supersed ...

References

{{reflist Sound measurements Noise pollution Aviation law

Computation of EPNdB

See also

References