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IEVref:801-22-13ID:
Language:enStatus: Standard
Term: spectrum density level
Synonym1: spectrum level
[Preferred]
Synonym2:
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Definition: level of the limit, as the width of the band approaches zero, of the ratio of a specified quantity distributed within a frequency band to the width of the band

NOTE 1 – The kind of quantity must be specified, such as by (squared) sound pressure spectrum level.

NOTE 2 – In view of the fact that filters have finite bandwidths, practically the sound pressure spectrum level Lps is obtained for the centre frequency of the band by the formula:

L ps =10 log 10 ( p 2 /B ) ( p 0 2 / B 0 ) dB MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbbjxAHXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaeqabiGaciGacaqadmaadaqaaqaaaOqaaiaadYeadaWgaaWcbaGaaeiCaiaabohaaeqaaOGaeyypa0JaaGymaiaaicdacaaMc8UaaGPaVlaabYgacaqGVbGaae4zamaaBaaaleaacaaIXaGaaGimaaqabaGcdaWcaaqaamaabmaabaWaaSGbaeaacaWGWbWaaWbaaSqabeaacaaIYaaaaaGcbaGaamOqaaaaaiaawIcacaGLPaaaaeaadaqadaqaamaalyaabaGaamiCamaaDaaaleaacaaIWaaabaGaaGOmaaaaaOqaaiaadkeadaWgaaWcbaGaaGimaaqabaaaaaGccaGLOaGaayzkaaaaaiaaysW7caqGKbGaaeOqaaaa@4FD3@

where p and p0 are respectively the given field quantity and the reference quantity; B et B0 are respectively the effective bandwidth of the filter and the reference bandwidth of 1 Hz.

When Lp is the band pressure level observed through the filter, the above relation reduces to

L ps = L p log 10 ( B/ B 0 )dB MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbbjxAHXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaeqabiGaciGacaqadmaadaqaaqaaaOqaceaaK=GaamitamaaBaaaleaacaqGWbGaae4CaaqabaGccqGH9aqpcaWGmbWaaSbaaSqaaiaabchaaeqaaOGaeyOeI0IaaeiBaiaab+gacaqGNbWaaSbaaSqaaiaaigdacaaIWaaabeaakmaabmaabaWaaSGbaeaacaWGcbaabaGaamOqamaaBaaaleaacaaIWaaabeaaaaaakiaawIcacaGLPaaacaaMc8UaaGjbVlaabsgacaqGcbaaaa@4A77@


Publication date:1994-07
Source:
Replaces:
Internal notes:2017-06-02: Cleanup - Remove Attached Image 801-22-131.gif

2017-06-02: Cleanup - Remove Attached Image 801-22-132.gif
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