Measurement and Modeling of High‐Frequency Acoustic Properties in Fine Sandy Sediments

Abstract

The object of this study was to obtain the acoustic properties of fine sandy sediments with approximately 22% clay content from the East China Sea Shelf. This study conducted the in situ acoustic measurement to measure the sound speed and attenuation, and eight sediment cores were collected and measured the wet bulk density, porosity, and mean grain size in laboratory environment. The correlations between in situ sound speed ratio and physical properties show good accordance with two empirical equations, while the in situ attenuation factor deviated the regression curves. Both the sound speed ratio and the attenuation data show the obvious change against the measurement frequency. The comparisons of the measured sound speed ratio and attenuation to the Biot-Stoll model predictions were performed. The sound speed ratio dispersion agrees well with the model prediction, when the permeability and pore size were calculated using the extended Kozeny-Carman's equation and the extended Hovem's equation. The attenuation data in this study accords better with the prediction curves reported for fine sediments than that for coarse sediments from the 1999 Sediment Acoustics Experiment.

Intertidal Soundscapes of Hardened and Living Shorelines: A Case Study of Habitat Enhancement

“…Attenuation through plants may also exhibit seasonal variation related to changes in above‐ground biomass and bubble production (Lee et al, 2023). In addition to plants, the introduction of both artificial structures and sand at the living shoreline could have also had meaningful effects on attenuation through changes to sound speed through solid structures, the possible introduction of gas pockets, the scattering properties of different sediments and variation in effects based on frequency (Li et al, 2019; Nyborg & Rudnick, 1948; Rogers & Cox, 1988; Wang et al, 2021; Yang & Tang, 2017). While not true for this study, it may still be possible that the specific types of habitat structures used in a living shoreline construction could so negatively impact sound propagation that even if more sound‐producers were present at the site, the overall nearby received sound levels could be similar or lower than if no living shoreline was present (Figure 1).…”

Time difference auto‐extraction methods for in situ sound speed measurements in seafloor sediments

“…The acoustic signal data were collected using the ballast in situ acoustic measurement system (BISAMS) (Figure 4), developed by the First Institute of Oceanography of the Ministry of Natural Resources. The BISAMS has been successfully used in the South China Sea and the East China Sea (Li et al., 2019; Wang et al., 2018). The system operates by using self‐weight ballast penetration.…”

“…Compared with the sampling measurement, in situ measurement introduces less disturbance to the seafloor sediment (especially deep‐sea soft sediments), and the environmental temperature and pressure will not change during the measurement, resulting in more accurate results that reflect the actual state of the seafloor sediments. Various techniques have been developed for acoustic in situ measurement of seafloor sediment, mainly including the in situ sediment acoustic measurement system (Richardson & Briggs, 1996), the acoustic lance (Gorgas et al., 2002), the hydraulic‐driven in situ sediment acoustic measurement system (Liu et al., 2013), the acoustic coring system assembled with a gravity core (Megan et al., 2019), the drag‐type in situ acoustic measurement system (Hou et al., 2014), the sediment acoustic‐speed measurement system (SAMS) (Yang & Jackson, 2020) and the ballast in situ acoustic measurement system (Li et al., 2019; Wang et al., 2018). These techniques have been widely applied in studying the acoustic properties of seafloor sediment in different marine regions.…”

High-Frequency Dependence of Acoustic Properties of Three Typical Sediments in the South China Sea

“…The blue line is the coarse sand sediment measured during the sediment acoustics experiment in 1999 (SAX99) by Williams et al [1], and the measurements span the frequency range of about 125 Hz-400 kHz, and the permeability of the coarse sand is 2.5 × 10 −11 . The red line is the fine sand sediment measured in the East China Sea shelf [21], with a frequency range of 30-87 kHz, including the in situ data with the measured frequency of 30 kHz, and the sediment core measurement data with the frequencies range of 47-87 kHz, and the permeability of the fine sand is 3.77 × 10 −12 . The green line is the sandy silt sediment measured in Currituck Sound, North Carolina [22], the compressional wave sound speed and attenuation were measured in the frequency band of 5-100 kHz, and the permeability of the sandy silt is 8.5 × 10 −12 .…”