IEVref: 801-32-62 ID: Language: en Status: Standard Term: source level Synonym1: sonar source level Synonym2: SL [Admitted] Synonym3: Symbol: LS 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 positionNote 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 µPa2m2 and the reference value for propagation loss is 1 m2.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 Source: Replaces: Internal notes: CO remarks: TC/SC remarks: VT remarks: Domain1: Domain2: Domain3: Domain4: Domain5: