About the ESI noise score
The total air noise score emitted by the ship is the weighted sum of:
- The found sound power level of the broadband noise in dB(A)
- The sound power level in the frequencies lower or equal to 160Hz in dB(A)
- The presence of a noise measurement report.
The relevant formulas can be found in Chapter 5 of the Best Practice Guide.
Regarding noise measurements
The measurements onboard a vessel must be done by a certified acoustician, following the NEPTUNES protocol. The measurement report is valid for five years. In case significant changes have been carried out on the vessel a new report must be sent in. Significant changes are replacements of noise emitting equipment or retrofitting, etc. The measurement report shall be sent to the ESI administrator. The report will be checked by an expert. The expert will check if the right methodology is applied. All information sent will be handled confidentially. One can fill in the measurement results on the ESI website. Principals may also use the noise measurements promoted by Lloyds register. The Lloyd system (with certificate) is almost the same as the NEPTUNES protocol. So, it is alright to fill in the data from a Lloyds report into a NEPTUNES form; this then equals a report and gives points for parts 1 and 2. Still, the report must be sent to the ESI administrator. Please refer to the ESI website which will be optimized in the coming months as far as the subject of noise is concerned.