Composing soundscapes from real-time acoustic data streams

Abstract

The growing scientific and societal concern about the effects of underwater sound on marine ecosystems has been recently recognized through the introduction of several international initiatives aiming at measuring the environmental impact of ocean noise on large spatial and temporal scales. From a regulatory perspective, the European Marine Strategy Framework Directive includes noise as one of 11 descriptors to determine Good Environmental Status of the oceans. The Directive specifically requires Member States to provide a measure of annually averaged noise. The LAB has developed a software package that measures sound levels and monitors acoustic sources in real-time; this software was used for the LIDO project and is now operating to provide industry with an environmentally responsible approach (CSA, www.oceansound.com). The system is currently operating worldwide from several wired and radio-linked observatories. Recently, through a zero-cost contract with the CTBTO (Preparatory Commission for the Comprehensive nuclear-Test Ban Treaty Organization), years of data from hydroacoustic stations were analyzed to look for background noise trends and to detect cetacean presence. Here, we present the analysis of four CTBTO platforms, each covering 42 months of data, focusing especially on the estimation of background noise levels and the measurement of noise contributions from anthropogenic sources.