An underwater sound source includes an acoustical driver, a controller of the acoustical driver, and a resonant tube acoustically coupled to the acoustical driver. The resonant tube has a pair of slotted portions, in which each slotted portion is disposed along the length of the resonant tube at a location corresponding to a node of a harmonic of the resonant tube. The sound system is configured to emit an output signal within a bandwidth defined by a dual resonance characteristic of the resonator tube. The sound source may also include a pair of coaxial tubular sleeves disposed around the resonant tube, each sleeve configured to slidably cover one of the slotted portions, and tune the resonance frequency of the tube over a wide range. At a high frequency end, when slots are uncovered, the frequency response of the resonant tube obtains a dual-resonant form.

An underwater sound source includes an acoustical driver, a controller of the acoustical driver, and a resonant tube acoustically coupled to the acoustical driver. The resonant tube has a pair of slotted portions, in which each slotted portion is disposed along the length of the resonant tube at a location corresponding to a node of a harmonic of the resonant tube. The sound system is configured to emit an output signal within a bandwidth defined by a dual resonance characteristic of the resonator tube. The sound source may also include a pair of coaxial tubular sleeves disposed around the resonant tube, each sleeve configured to slidably cover one of the slotted portions, and tune the resonance frequency of the tube over a wide range. At a high frequency end, when slots are uncovered, the frequency response of the resonant tube obtains a dual-resonant form.

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.

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.

An acoustically resonating medium has one or more nodes and anti-nodes. Insulating a first side of a resonating medium at a node from ambient air and exposing the opposite second side of the resonating medium at the node to ambient air results in thrust in the direction of the first side. Insulating the second side of a resonating medium at an anti-node from ambient air and exposing the first side of the medium at the anti-node to ambient air also results in thrust in the direction of the first side.

The invention relates to hydroacoustics and more specifically to hydroacoustic devices comprising, disposed in a single housing, a converter of liquid-medium oscillations and electrical signals, capable of receiving and/or transmitting hydroacoustic signals, the converter being disposed on a board which is connected to a switch cable for providing power and transmitting electrical signals, and may be used as a receiver and/or transmitter of hydroacoustic signals in water. According to the invention, the housing of the to hydroacoustic device is formed by the outer surfaces of the converter and board, and by a protective material which coats all of said surfaces, said material allowing for a transmission of hydroacoustic oscillations and being capable of transitioning from a highly-elastic or viscous-flow state to a solid state. The achieved technical result consists in simplifying the design of the device.

The invention relates to hydroacoustics and more specifically to hydroacoustic devices comprising, disposed in a single housing, a converter of liquid-medium oscillations and electrical signals, capable of receiving and/or transmitting hydroacoustic signals, the converter being disposed on a board which is connected to a switch cable for providing power and transmitting electrical signals, and may be used as a receiver and/or transmitter of hydroacoustic signals in water. According to the invention, the housing of the to hydroacoustic device is formed by the outer surfaces of the converter and board, and by a protective material which coats all of said surfaces, said material allowing for a transmission of hydroacoustic oscillations and being capable of transitioning from a highly-elastic or viscous-flow state to a solid state. The achieved technical result consists in simplifying the design of the device.

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.