Analysis of acoustic noise emissions from marine vessels

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JASCO Applied Sciences Ltd. specializes in collecting, analyzing, and assessing underwater acoustic data for**environmental impact assessments of underwater noise for the oil and gas, marine construction, fisheries, and**defence sectors. A particular project, in collaboration with Transport Canada, has been to monitor underwater**acoustic noise due to marine traffic in the Strait of Georgia, adjacent to Vancouver Island and the city of**Vancouver. Through covariate analysis of measured acoustic data, in combination with automatic identification**system (AIS) data, such as vessel class, size, and speed of passing vessels, JASCO is constructing a predictive**marine vessel noise model that may influence regulation to reduce the environmental impact of marine traffic**noise.**One significant problem is a high degree of variability in the measured acoustic levels associated with a given**set of vessel characteristics. It is believed that this variability originates from a combination of variability in**engine noise, shaft and propeller noise, and cavitation of the flow around the vessel hull and propeller(s), all of**which can vary independently of the parameters currently considered in the model. Of these potential noise**sources, cavitation is believed to be the dominant source of noise source for marine vessels and has been the**focus of many recent studies of ship noise.**Identification of parameters that govern cavitation noise is of significant benefit to JASCO. This**characterization will enable the company to determine how cavitation noise influences the recorded acoustic**spectra, so that noise emission models can be improved. This enhanced knowledge will improve the**company's ability to perform environmental impact assessments of marine traffic, which could also have a**significant impact on determining optimal vessel designs and operating regimes.