Measuring & Mapping Particle Motion

One of the objectives of the SATURN project is to develop the capability to produce maps of metrics based on sound particle motion, to which many fish and invertebrate species are sensitive.


SATURN partners TNO and JASCO have compared the capabilities of their acoustic models for selected benchmark scenarios, to verify the appropriate implementation of the models. The next step is to validate these models against experimental data.


Left: TNO's particle measurement rig. Right: Deploying the rig.



To acquire data for a realistic offshore location in shallow water, TNO has deployed its particle motion measurement rig at a location in the North Sea, in the The Hague offshore test area. This area has the advantage that it is relatively easily accessible for experiments with controlled sound sources and with opportunities to measure individual ship passages of opportunity without too much interference from other ships.


The TNO stand-alone measurement rig includes the VHS-100 vector sensor, that measures sound pressure as well as sound particle acceleration in three orthogonal directions, connected to a 4-channel recording system.



Sensor location plotted on top of the Marie Traffic ship density map.
Sensor location plotted on top of the Marie Traffic ship density map.

The rig was placed on Tuesday 17 May 2022, at 2.5 km outside the port of Scheveningen. It was deployed from a rigid-hull inflatable boat (RHIB), on the seabed at about 15 depth. On that day it collected data from the sound produced by the RHIB during various runs at different distances, and by a small controlled airgun source. These are to be used for the model validation. The rig was recovered on Friday 20 May 2022. Over these three days, it has continuously recorded sound pressure and sound particle acceleration, generated by natural sources (such as surface wave breaking, and rain) as well as the sound from anthropogenic sources such as passing ships. These data will provide more insight in typical background noise levels and signals from passing ships.



View from the RHIB, showing the town of Scheveningen in the distance, the small surface buoy above the rig to the left, and a big cardinal buoy to the right.
View from the RHIB, showing the town of Scheveningen in the distance, the small surface buoy above the rig to the left, and a big cardinal buoy to the right.

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