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 sound wave delivery structure of the present invention comprises unit structure cells each formed to have a cubic shape and comprising a column portion formed on a region corresponding to sides, and a space portion formed in an internal region surrounded by the column portion. There are a plurality of unit structure cells which are successively arranged in a first direction, in which sound waves are delivered, and a second direction crossing the first direction.

A sonar device includes a support having negative buoyancy and a linear acoustic reception antenna comprising an elongated body that is elongated from a first end to a second end, the elongated body being connected by the first end at a connection point that is fixed relative to the support, the sonar device being able to be in a reception configuration, wherein the antenna body and the support are fully submerged and wherein the antenna body is able to be in a vertical orientation, wherein it extends substantially vertically from the first end to the second end toward the seabed, the sonar device comprising orientation adjustment means for adjusting, when the sonar device is in the reception configuration and the support is fixed relative to the terrestrial reference frame, an angle of elevation and an azimuth of the second end in the reference frame connected to the support centered on the connection point.

An electro mechanical piezoelectric under water sound acoustic projector transducer which does not interfere with adjacent hydrophone reception and is mainly controlled at the electrical input is presented here. The method recognizes that the main interference with the adjacent hydrophone is mostly due to the resonance of the projector when not transmitting and is excited by the incoming acoustic wave reflected from the target signal originally initiated by the projector. Means for accomplishing this are shown to be simple to implement on current or new projector systems. The process uses an electrical resistor that absorbs the incoming acoustic wave as if the resistor were a mechanical damper and the projector transducer were acoustically transparent.

Underwater voice communication devices and associated methods are described. According to one aspect, an underwater voice communication device includes a voice chamber comprising a face seal which is configured to form at least a substantially watertight seal with respect to a mouth of a first user, wherein the voice chamber comprises an internal volume, an earpiece comprising an ear seal which is configured to form at least a substantially watertight seal with respect to an ear of a second user, wherein the earpiece comprises an internal volume which is in fluid communication with the internal volume of the voice chamber, and wherein the internal volumes of the voice chamber and earpiece communicate voice sound waves from the mouth of the first user to the ear of the second user.

An apparatus in a surrounding liquid and methods of using same. The apparatus includes an acoustic Fresnel zone plate comprising a compliant frame, a substrate connected to the frame, and an acoustic diffraction grating connected to the substrate. The acoustic diffraction grating includes a plurality of concentric rings or a plurality of concentric islands. The substrate is acoustic-impedance-mismatched with the acoustic diffraction grating. The acoustic Fresnel zone plate includes at least one acoustic focal spot. The substrate is acoustic-impedance-mismatched with the surrounding liquid and the acoustic diffraction grating is acoustic-impedance-matched with the surrounding liquid, or the substrate is acoustic-impedance-matched with the surrounding liquid and the acoustic diffraction grating is acoustic-impedance-mismatched with the surrounding liquid.

A device for reducing underwater sound energy and propagation, whereby the device includes at least one bubble generation unit and an air conduit for supplying pressurized air to the bubble generation unit, whereby the bubble generation unit has a fluidic oscillator for generating one or more pulsating air flows from a constant air flow, and whereby preferably the fluidic oscillator has an adjustable oscillation frequency, and a method for using such a device for reducing underwater sound propagation, whereby the air conduit and the bubble generation unit are placed underwater, whereby pressurized air is supplied to the air conduit and whereby air bubbles are generated by the bubble generation unit.

A device for reducing underwater sound has a holding device and a hydrosound damper with noise reducing elements. The device has a transport housing for transporting the hydrosound damper, a first end of the underwater sound damper being fixed to the transport housing and the transport housing being connected to a holding device via a support device has a cable winch with a support cable arranged on the transport housing and has a motor-driven drum, wherein using the support device, the transport housing is lowered from the holding device to the sea floor.

A device for reducing underwater sound has a holding device and a hydrosound damper with noise reducing elements. The device has a transport housing for transporting the hydrosound damper, a first end of the underwater sound damper being fixed to the transport housing and the transport housing being connected to a holding device via a support device has a cable winch with a support cable arranged on the transport housing and has a motor-driven drum, wherein using the support device, the transport housing is lowered from the holding device to the sea floor.

Sonar systems and related methods are provided. A sonar system for generating one or more sonar images includes first and second transducer elements each having at least one emitting face. The sonar system also includes a sonar signal processor in electronic communication with the first and second transducer elements to cause transmission of signals from the first and second transducer elements to cause at least one first acoustic beam to be emitted from the first emitting face in a first beam direction and at least one second acoustic beam to be emitted from the second emitting face in a second beam direction. The first and second transducer elements are positioned such that a gap is formed therebetween. The gap is configured to facilitate movement of a fluid therein so as to contribute to an emission of sound power in both the first beam direction and the second beam direction.