Acoustic Properties of Marine Sediments

Marine sediments exhibit a range of acoustic behaviours determined by their physical composition and structure. Sound waves travelling through the seabed are influenced by parameters such as grain size, porosity, density and fluid content. High-porosity silty or clay-rich sediments attenuate high-frequency signals more strongly than coarser sands, while compacted silts and sands yield higher sound speeds and lower attenuation. Acoustic impedance contrasts at sediment–water and sediment–sediment interfaces govern reflection and scattering patterns recorded by sub-bottom profilers and multibeam echo sounders. Frequency-dependent dispersion and absorption arise from viscous and elastic interactions within the porous framework, and are encapsulated in poroelastic models that couple fluid motion and grain skeleton dynamics. Understanding these acoustic properties underpins marine geophysics, environmental monitoring, resource exploration and underwater communication, offering non-invasive means to characterise seabed stratigraphy, assess gas-hydrate deposits, map benthic habitats and monitor sediment transport processes on a global scale.

Research from Nature Portfolio

Recent studies have advanced inversion techniques using sub-bottom profiling data from autonomous underwater vehicles. By applying poroelastic models to measured reflection coefficients at kHz frequencies, researchers have derived porosity, density and mean grain size of surface sediments across continental slopes with deviations under 15% from laboratory analyses. This approach has revealed systematic fining of sediments with increasing depth and refined the spatial resolution of sediment-property maps. In parallel, foundational theoretical frameworks revisited the Biot–Stoll model to reconcile frequency-dependent dispersion and attenuation in mixed-grain sediments, resulting in improved predictions for sediment acoustic responses under varying hydrodynamic conditions.

Acoustic Properties of Marine Sediments publication trend

The graph below shows the total number of articles in acoustic properties of marine sediments across all publications each year (not limited to Nature Index journals).

Technical terms

Acoustic impedance: The product of sediment density and sound speed, controlling reflection strength at interfaces.

Attenuation: The loss of acoustic energy in sediments due to absorption and scattering as a wave propagates.

Poroelasticity: A theoretical framework coupling fluid flow and elastic deformation in porous media to describe acoustic dispersion and attenuation.

Sub-bottom profiler: An acoustic instrument that emits low-frequency pulses to image sediment layers beneath the seafloor.

Reflection coefficient: The ratio of reflected to incident acoustic wave amplitude at a boundary between two media.

References

1. Inversion of Sub-Bottom Profile Based on the Sediment Acoustic Empirical Relationship in the Northern South China Sea. Remote Sensing (2024).
2. Inversion of the physical properties of seafloor surface sediments based on AUV sub-bottom profile data in the northern slope of the South China Sea. Scientific Reports (2021).
3. Physical properties and in situ geoacoustic properties of seafloor surface sediments in the East China Sea. Frontiers in Marine Science (2023).
4. Predicting the Sound Speed of Seafloor Sediments in the East China Sea Based on an XGBoost Algorithm. Journal of Marine Science and Engineering (2022).