IEVref: | 801-32-62 | ID: | |

Language: | en | Status: Standard | |

Term: | source level | ||

Synonym1: | sonar source level | ||

Synonym2: | SL [Admitted] | ||

Synonym3: | |||

Symbol: | L_{S}
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Definition: | sum of sound pressure level ${L}_{p}\left(x\right)$, at position $x$, and propagation loss from the source position to the receiver position, ${N}_{\text{PL}}=\left(x-{x}_{0}\right)$, where ${x}_{0}$ is the source position Note 1 to entry: In equation form, ${L}_{\text{S}}={L}_{p}+{N}_{\text{PL}}$. Note 2 to entry: Source level is only defined for an equivalent monopole (point) source, where the sonar is treated as a point source of sound. For this treatment to be valid, the measurement position, $x$, shall be in the acoustic far field of the sonar source. Note 3 to entry: This definition of source level is consistent with that of ISO 18405, which is more generally applicable, as it is valid for a finite source. Note 4 to entry: When sound pressure level is defined as ten times the logarithm of the mean square pressure, the reference value for source level is 1 µPa Note 5 to entry: When sound pressure level is defined as twenty times the logarithm of the root-mean-square pressure, the reference value for source level is 1 µPa·m and the reference value for propagation loss is 1 m. Note 6 to entry: This note applies to the French language only. | ||

Publication date: | 2021-02 | ||

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Note 1 to entry: In equation form, ${L}_{\text{S}}={L}_{p}+{N}_{\text{PL}}$.

Note 2 to entry: Source level is only defined for an equivalent monopole (point) source, where the sonar is treated as a point source of sound. For this treatment to be valid, the measurement position, $x$, shall be in the acoustic far field of the sonar source.

Note 3 to entry: This definition of source level is consistent with that of ISO 18405, which is more generally applicable, as it is valid for a finite source.

Note 4 to entry: When sound pressure level is defined as ten times the logarithm of the mean square pressure, the reference value for source level is 1 µPa^{2}m^{2} and the reference value for propagation loss is 1 m^{2}.

Note 5 to entry: When sound pressure level is defined as twenty times the logarithm of the root-mean-square pressure, the reference value for source level is 1 µPa·m and the reference value for propagation loss is 1 m.

Note 6 to entry: This note applies to the French language only.