A system for reducing noise emissions in underwater environments is presented. The system can be extended to applications in any two-fluid environments where one fluid (gas) is contained in an enclosed resonator volume connected to the outside environment at an open end of the resonator body. The resonators act as gas-containing (e.g., air) Helmholtz resonators constructed into solid panels that are submerged in the fluid medium (e.g., sea water) in the vicinity of a noise generating source. The oscillations of the trapped air volume in the resonators causes reduction of certain noise energy and a general reduction in the transmitted noise in the environment of the system.

An apparatus for generating acoustic waves in an aquatic environment through the use of linear motors mounted on a frame is disclosed herein. The linear motors can reciprocate at a first frequency which is transmitted through a transmission element and to a sound emitting surface. The structure of the apparatus can generate acoustic waves across a broad frequency to measure subterranean formations.

In certain examples, methods and circuit-based apparatuses involve or are directed to a transducer to be operated via at least one resonance frequency of the transducer, and to a tunable circuitry (e.g., negative capacitance control and/or resistance control) to change the resonance frequency and/or a bandwidth around the resonance frequency. In more specific aspects, a tunable negative capacitance control may be used to change the resonance frequency and/or damping resistance control without degrading a degree of sensitivity provided by the transducer. Another example, specific to a method, involves: operating a transducer, coupled to a negative capacitance, at a resonance frequency of the transducer; and changing or setting a characteristic concerning the resonance frequency by using a tunable circuit to effect a change of the resonance frequency and/or a bandwidth around the resonance frequency.

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.

An amplifier circuit to be used in a sonar is described. The amplifier circuit includes a transducer and a matching circuit. The transducer has an impedance characteristic having a resonance frequency and an anti-resonance frequency higher than the resonance frequency. The matching circuit is connected to the transducer. The impedance characteristic of the transducer connected to the matching circuit has a first resonance frequency and a second resonance frequency higher than the first resonance frequency.

An underwater detection device includes a transmitter, a receiver, an actuator, a controller, and a signal processor. The transmitter transmits a transmission wave. The receiver receives a reflection wave of the transmission wave. The actuator rotates the transmitter and the receiver in a mutually synchronized fashion. The controller makes the transmitter transmit a plurality of transmission waves at mutually different frequencies in order, for every given unit rotation angle. The signal processor generates an echo signal for indication in a direction of the unit rotation angle based on a reception signal at each of the frequencies acquired from a range of the unit rotation angle.

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.