Underwater ambient sound has been recently re-addressed in regard to the impact of anthropogenic sound from commercial shipping on marine life. Passive acoustic monitoring provides the overall ambient sound levels at a given location and is often used to calibrate the sound propagation modeling for assessing ambient sound levels in larger marine areas. To quantify the pressure on the environment, the proportion of the anthropogenic component in the total measured levels of the monitored sound should be properly assessed. The present paper addresses the methodology for categorisation of the measured sound into its wind-driven natural and anthropogenic components.