Disclosed are devices and methods for marine geophysical surveying. An example device may comprise a shell, a base plate, wherein the base plate is coupled to the shell, a driver disposed within the shell, an inner spring element disposed within the shell, wherein the inner spring element is coupled to the driver, wherein outer ends of the inner spring element are coupled to outer ends of the inner spring element at spring element junctions, an outer spring element disposed within the shell, wherein outer ends of the outer spring element are coupled to the spring element junctions, and a back mass disposed on the outer spring element.

Embodiments relate to marine seismic vibrators for use in seismic surveying and associated methods of use. An embodiment provides a marine seismic vibrator comprising: a shell having a spring constant selected to provide a first resonance frequency within an operational frequency range of about 1 Hz and about 300 Hz; a driver disposed within the shell and having a first end and a second end; and a spring element coupled to the shell between the first end and the second end of the driver, wherein the spring element has a second mode of oscillation that provides a second resonance frequency within the operational frequency range.

An air pulse generating element is disclosed. The air pulse generating element includes a front faceplate; a back faceplate; a front supporting element; a back supporting element; a folded membrane, configured to form a front chamber and a back chamber, and comprising a plurality of membrane units; wherein the plurality of membrane units are parallel and sequentially connected and an end of the folded membrane is connected to the back faceplate via the back supporting element and another end of the folded membrane is connected to the front faceplate via the front supporting element; and a plurality of valves controlling a plurality of air flow channels between the front chamber toward either a front space or a back space; wherein the plurality of membrane units are configured to perform horizontal deformation to squeeze air in and out of the front or back chamber with operations of the plurality of valves.

In accordance with embodiments of the present disclosure, a flextensional transducer for underwater operation includes a driving element and a stave. The stave is made from a material with elastic properties and has a porous structure. The porous structure is adapted to be modelled such that when in use, said porous structure of the stave is of an arbitrary alignment with respect to, for instance, the driving element, and has a degree of porosity. The degree of porosity is such that the elastic properties and vibrational frequency response of the stave can be customised with respect to its intended use.

A synthetic jet assembly includes a synthetic jet having a cavity and an opening formed therein. The synthetic jet assembly also includes an actuator element coupled to a second surface of the body to selectively cause displacement of the second surface, and a control unit electrically coupled to the actuator element. The control unit is configured to transmit a multi-frequency drive signal to the actuator element, the multi-frequency drive signal comprising a cooling frequency component and an acoustic frequency component superimposed on the cooling frequency component. The cooling frequency component causes a cooling jet to eject from the opening of the body. The acoustic frequency component produces a desired audible output.

An ultrasonic transducer having a container, a base an actuator and a membrane system. The membrane system can include a membrane, a mesa and a standoff. The mesa can be shaped to achieve one or more target frequencies and other target vibrational properties, such as amplitudes. The actuator may be a flexure having one or more electroactive materials, such as piezoelectric and/or electrostrictive materials. The flexure may be fixed at one end to a wall of the container be in communication with the membrane system at or around its other end. The actuator may be in contact with the membrane system through the mesa and/or the standoff. The standoff may include an adhesive filled with beads to achieve a specific thickness.

A sound quality or quality control apparatus includes: at least one electrode; and a controller configured to control at least one of a voltage value, a current value, a frequency, or a phase of voltage or current applied to the electrode, in which while an object is disposed to face the electrode, the object having liquid inside or on a surface and containing at least one of wood, leather, metal, an inorganic material, an organic material, an animal- or plant-derived material, or a composite material, at least one of an electric field, a magnetic field, an electromagnetic field, electromagnetic waves, sound waves or ultrasonic waves generated by the electrode, is controlled to control a state of the liquid present inside or around the object that is disposed to face the electrode, so that a sound quality or quality of the object is controlled.

Flextensional transducers and methods of using flextensional transducers. The transducer includes a piezoelectric element and may include at least one endcap coupled with the piezoelectric element. The endcap may have an outer portion formed of a first material and an inner portion formed of a second material having a greater flexibility than the first material. The endcap may be coupled with an annular piezoelectric element near either its outer circumference or its inner circumference. The piezoelectric element may be a planar disk or have a curved bowl-shape. The transducer may be coupled with, and at least partially restrained by, a support structure. The transducer may also be configured to permit light to pass therethrough.

A sound transducer, including a diaphragm and at least one piezoactuator, which is situated in an operative connection to the diaphragm, the oscillation direction of the piezoactuator being situated at least generally perpendicularly in relation to the oscillation direction of the diaphragm, at least one lever element being situated between the diaphragm and the piezoactuator, which connects the diaphragm to the piezoactuator and is designed to convert oscillations of the piezoactuator into oscillations of the diaphragm and vice versa, and a clamp connection being formed between the at least one lever element, and the piezoactuator. The clamp connection is formed between an end face of the piezoactuator situated in the oscillation direction of the piezoactuator and the at least one lever element, and the piezoactuator is situated under an axial pre-tension force extending in the oscillation direction of the piezoactuator by the at least one lever element.

An acoustic projector is provided with an enclosure having a semi-permeable membrane on one side. High salinity liquid is injected at the enclosure to increase osmotic pressure. Valves thereafter allow free flooding between the enclosure and surrounding seawater to equalize the pressure. Transient pressure in the enclosure generates a pressure pulse that propagates from the semi-permeable membrane. The timing of the injection by salt jets and the free-flooding valves enables a repeatable acoustic pulse at low frequencies and a determinable upper frequency. If the acoustic projector is mounted to be conformal to the hull of a ship; the acoustic projector includes a free-flowing region on one side of a semi-permeable membrane and valves. When the valves are opened; the other side of the membrane is free-flooded. Salt jets inject high salinity liquid into an enclosure to increase pressure with the result of an acoustic pressure pulse.