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IEVref: | 801-22-13 | ID: | |

Language: | en | Status: Standard | |

Term: | spectrum density level | ||

Synonym1: | spectrum level [Preferred] | ||

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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 $L}_{\text{ps}}=10\text{\hspace{0.17em}}\text{\hspace{0.17em}}{\text{log}}_{10}\frac{\left({p}^{2}/B\right)}{\left({p}_{0}^{2}/{B}_{0}\right)}\text{\hspace{0.17em}}\text{dB$
where When
${L}_{\text{ps}}={L}_{\text{p}}-{\text{log}}_{10}\left(B/{B}_{0}\right)\text{\hspace{0.17em}}\text{dB}$ | ||

Publication date: | 1994-07 | ||

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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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Domain5: |

$L}_{\text{ps}}=10\text{\hspace{0.17em}}\text{\hspace{0.17em}}{\text{log}}_{10}\frac{\left({p}^{2}/B\right)}{\left({p}_{0}^{2}/{B}_{0}\right)}\text{\hspace{0.17em}}\text{dB$

where *p* and *p*_{0} are respectively the given field quantity and the reference quantity; *B* et *B*_{0} are respectively the effective bandwidth of the filter and the reference bandwidth of 1 Hz.

When *L*_{p} is the band pressure level observed through the filter, the above relation reduces to

${L}_{\text{ps}}={L}_{\text{p}}-{\text{log}}_{10}\left(B/{B}_{0}\right)\text{\hspace{0.17em}}\text{dB}$