The Sound Risk Indicator Tool addresses the need for rapid assessment of design changes to noisy activities. It accounts for most marine fauna and presents the result as a single number, facilitating easy comparisons.
As sound propagation modelling in the marine environment in complex and often slow, with processing durations of several hours to days, Equinor and Irwin Carr have developed the SRI tool. This tool uses a conservative method to model the sound propagation and uses information about a noisy activity to predict if changes will result in increased or decreased impact on marine fauna. It accomplishes this in seconds to minutes and considers the frequency dependent vulnerability (weightings) of eleven animal groups that cover all marine mammals, most fishes and turtles for a total of 33 threshold values for both impulsive (Lpk and SEL) and continuous noise (SEL).
In this way, changes to a complex activity, with many moving sources, source levels and receivers, can quickly be evaluated for their effect on the environment. The SRI tool compresses everything into a single number that indicates the relative impact, while allowing the user to dig deeper into the data to discover where to change the design to most effectively mitigate impact.
The tool will accept information about the noisy activity either as band levels or as a timeseries, a common format from commercially available seismic array models and also the movement of the noise source(s). In absence of source data, the tool offers some models for generating source levels from large vessels and from seismic arrays.
The tool’s simple propagation modelling provides the user with a good estimate of the highest possible impact. This means that if the tool predicts little to no impact, the user can be confident that further advanced modelling will similarly show little to no impact.
 Based on: “Duncan AJ, Parsons MJG. 2011. How Wrong Can You Be? Can a Simple Spreading Formula Be Used to Predict Worst-Case Underwater Sound Levels? Proceedings of Acoustics 2011, 87”