Acoustical properties of water saturated and gassy sediments are observed to be significantly different. The present state of knowledge of the acoustical properties of saturated sediments, gassy water, and gassy sediments is reviewed. The dynamics of bubbles in water and in various solid materials, including sediments, are experimentally examined in a companion paper. Pulsation resonance is exhibited by the bubbles in all materials examined. Predictions of bubble resonance frequency and damping are shown to agree with the measurements. Equations for sound speed and attenuation, based on the model of resonating gas bubbles, are shown to agree with published measurements in gassy sediments. Parameters required for predicting gassy sediment acoustical properties are identified. Ranges of values of these parameters for various sediments are discussed.

Acoustical properties of water saturated and gassy sediments are observed to be significantly different. The present state of knowledge of the acoustical properties of saturated sediments, gassy water, and gassy sediments is reviewed in a companion paper. The dynamics of bubbles in water and in various solid materials, including sediments, are experimentally examined here. Pulsation resonance is exhibited by the bubbles in all materials examined. Predictions of bubble resonance frequency and damping are shown to agree with the measurements. Equations for sound speed and attenuation, based on the model of resonating gas bubbles, are shown to agree with published measurements in gassy sediments. Parameters required for predicting gassy sediment acoustical properties are identified. Ranges of values of these parameters for various sediments are discussed.

As part of a program to measure in situ acoustic parameters of sediments, transducers capable of measuring shear-wave speed and attenuation in laboratory sediments have been designed and fabricated. Transducers consisting of an array of ceramic benders have been found to be the most useful in measuring shear-wave parameters of high-porosity laboratory sediments. Measurements of shear-wave speed and attenuation in kaolinite clay sediments have been made using the ceramic bender transducers. These clays exhibit calculated shear moduli as low as 1.7×105 dyn/cm2 with shear-wave speeds from 2 to 40 m/s and attenuations from less than 100 dB/m to more than 500 dB/m.

This is a summary of an experimental study to measure the acoustic properties of water-saturated sediments. The sediments used were laboratory prepared to allow control of physical parameters (such as grain size, volume concentration, compressibility, etc.) and to approximate natural sediments. Acoustic velocity and attenuation in the sediments were measured over the frequency range 4–600 kHz. Acoustic measurements were made at high frequencies by means of two probes inserted in the sediments, and at low frequencies by means of a specially constructed rigid-wall standing-wave tube. The data presented show the frequency dependence of attenuation and velocity in the laboratory-prepared sediments and the change in this frequency dependence with changes in physical parameters of the sediments. Sediments composed of pure kaolinite, or kaolinite and sand up to 15% (by weight), show an f1.37 frequency dependence of attenuation. Sediments with greater than 30% sand (by weight), including pure sand, exhibit an f0.5 frequency dependence of attenuation. The measured velocity dispersion approximately 2% over the frequency range 4–200 kHz. Velocity increases with frequency. All measurements reported are for sediments free of entrapped gas.

This is a summary of work done at DRL on measurement of acoustic properties of water-saturated sediments. The sediments used were laboratory-prepared to allow control of physical parameters (such as grain size, volume concentration, compressibility, etc.) and to approximate natural sediments. Acoustic velocity and attenuation in the sediments were measured over the frequency range 4–600 kc/sec. Acoustic measurements were made at high frequencies by means of two probes inserted in the sediments and at low frequencies by means of a specially constructed rigid-wall standing-wave tube. The data presented show the frequency dependence of attenuation and velocity in the laboratory-prepared sediments and the change in this frequency dependence with changes in physical parameters of the sediments. Sediments composed of pure clay or clay and sand up to 15% (by weight) show a f1.37 frequency dependence of attenuation. Sediments with greater than 30% sand (by weight), including pure sand, exhibit an f0.5 frequency dependence of attenuation. The measured dispersion is approximately 6% over the frequency range 4–600 kc/sec. Velocity increases with frequency. [Work sponsored by U. S. Navy Bureau of Ships.]