Quantification of airborne noise emitted by ships based on class notation

In addition to a number of other forms of environmental impact by shipping activities, airborne noise radiated by ships, too, has come to the attention of Regulatory Bodies in the latest years. The presence of strong acoustic sources on board, and the proximity of the port to inhabited zones represent the main technical aspect of the problem. To meet the demand for control of the airborne noise radiated by a ship, in 2019, the Lloyd's Register issued a class notation on airborne noise emissions by ships, setting a procedure for awarding this notation. Numerical models for the prediction of airborne noise propagation represents a favorable element for the evaluation and control of the airborne acoustical impact. This paper reports the application of this additional class notation and its effectiveness in characterizing the noise field radiated by a cruise ship. The performances of different software in terms of the reproduction of the noise field radiated by a ship and with specific reference to the predicted levels at normative reference distances have been carried out. Results shows the potentiality of this type of approach and first interesting conclusions as regard the radiated airborne noise from a large cruise ship.