There is currently a lack of consensus over how to average local shipping noise levels to assess the impact of such noise on marine life. Using data collected between Dec. 2011 and Apr. 2012 from an Ocean Sonics low-frequency hydrophone deployed at the VENUS Eastern Strait of Georgia site, this publication assesses various methods for averaging local shipping noise levels. The conclusion from this assessment is that mean sound pressure levels averaged in linear space are most relevant for determining the cumulative impact on marine life (below).
Reference
Merchant N.D., Blondel P., Dakin D.T., Dorocicz J. 2012. Averaging underwater noise levels for environmental assessment of shipping. The Journal of the Acoustical Society of America, 132(4), pp. EL343-EL349.