# BS ISO 18405:2017 pdf free

**BS ISO 18405**:2017 pdf free.Underwater acoustics一Terminology

product of the square of the distance from the acoustic centre (3.3.1.3) of a source, in a specified direction, r2, and time-integrated squared sound pressure (3.1.3.5) in the acoustic far field (3.3.1.1) at that distance, Ep(r), of a sound source, if placed in a hypothetical infinite uniform lossless medium of the same density and sound speed as the real medium at the location of the source, with identical motion of all acoustically active surfaces as the true source in the true medium

Note 1 to entry: In formula form, Fs,E= r2 Ep(r).

Note 2 to entry: Energy source factor is expressed in units of pascal squared metre squared second (Pa2 m2s).

Note 3 to entry: The frequency range shall be specified.

Note 4 to entry: The value of the energy source factor is independent of the distance, r.

Note 5 to entry: Energy source factor is a property of a transient sound source.

Note 6 to entry: The integration time for the exposure is the entire duration of the received pulse.

Note 7 to entry: The use of “energy” in the name of this term implies a quantity proportional to the time-integrated squared sound pressure.

Note 8 to entry: The hypothetical medium is unbounded in all directions.

Note 9 to entry: For a directional sound source such as a sonar projector, the direction is that of the principal axis unless stated otherwise.

Note 10 to entry: The distance can be specified from points in the source other than the acoustic centre without changing the value of the energy source factor.

Note 11 to entry: The numerical value of the energy source factor, when expressed in units of pascal squared metre squared second, is equal to the time-integrated squared sound pressure that would exist at a distance of 1 m from a hypothetical point monopole source, when expressed in units of pascal squared, if placed in the same hypothetical infinite uniform lossless medium for which the energy source factor is defined, and if the energy source factor of the hypothetical point source is equal to that of the true energy source factor in the specified direction. For this reason, it is common to use this hypothetical time-integrated squared sound pressure as an alternative metric to the energy source factor. BS ISO 18405 pdf download.