A photoacoustic apparatus may include: a ring transducer configured to measure a photoacoustic signal generated from an object, and including a hollow space that is provided as a travel path of light and ultrasonic waves; a mirror part disposed along a light path of the light transmitted from the ring transducer, and configured to reflect the light transmitted from the ring transducer, and the ultrasonic waves generated from the object, and to adjust magnification of the mirror part according to a number of apertures of the photoacoustic apparatus; and a fluid tank including a transparent film that allows the photoacoustic signal to pass through the fluid tank, and accommodating a fluid, the ring transducer, and the mirror part inside the fluid tank.

The objective of this invention is to provide an ultrasonic-wave transmitter/receiver with a fastening member that enables the case of such transmitter/receiver to be fastened reliably without impairing the usability of such transmitter/receiver during normal use. The ultrasonic-wave transmitter/receiver 10 comprises an ultrasonic transducer that transmits and receives ultrasonic waves; a case 50 that houses the ultrasonic transducer; and a cable 40 that suspends the case 50. The case 50 is of a hanging-bell shape comprising a lower-half part 51 having a bottom surface 52 and an outer-peripheral surface 53; and an upper-half part 61 having a structure of which the outer diameter gradually decreases toward the upper end. At least the lower-half part 51 of the case 50 is made of an elastic body. The groove 57 extending in the circumferential direction of the lower-half part 51 is formed on the outer-peripheral surface 53 of the lower-half part 51.

A cavity system, comprising: a cavity (2) comprising a cavity opening; and an acoustically reflective structure (18, 20) located at least partially within the cavity (2), the acoustically reflective structure (18, 20) comprising one or more acoustically reflective surfaces (24, 26, 30, 32), each acoustically reflective surface (24, 26, 30, 32) being oblique to a plane of the cavity opening (27). The one or more acoustically reflective surfaces (24, 26, 30, 32) may be arranged to reflect incident acoustic waves out of the cavity opening while avoiding reflection into a region (48) at or proximate to a leading edge (14) of the cavity (2).

A cavity system, comprising: a cavity (2) comprising a cavity opening; and an acoustically reflective structure (18, 20) located at least partially within the cavity (2), the acoustically reflective structure (18, 20) comprising one or more acoustically reflective surfaces (24, 26, 30, 32), each acoustically reflective surface (24, 26, 30, 32) being oblique to a plane of the cavity opening (27). The one or more acoustically reflective surfaces (24, 26, 30, 32) may be arranged to reflect incident acoustic waves out of the cavity opening while avoiding reflection into a region (48) at or proximate to a leading edge (14) of the cavity (2).

An acoustic reflector for a microphone to measure flyover noise generated by an aircraft. The microphone is configured to measure flyover noise generated by an aircraft flying on a preset path. The acoustic reflector includes at least a central portion having the shape of an ellipse having a major axis and a plurality of peripheral portions distributed around the central portion. The acoustic reflector allows edge effects to be attenuated at the low frequencies of the noise to be measured.

A sound diffuser includes a first annular control member, a second annular control member, and a third annular control member. The first annular control member includes a first communication hole and an annular inclined plate that surrounds the first communication hole and is inclined relative to an axial direction of the first communication hole. The second annular control member includes a second communication hole and an annular inclined plate that surrounds the second communication hole, houses the first annular control member therein, and is inclined relative to an axial direction of the second communication hole. The third annular control member has a plurality of third communication holes and surrounds the second annular control member.

A system for abating noise emanating from a kitchen electric appliance includes a base of a predetermined size, comprising a first instance of a noise reflecting material, so that said base is disposed underneath, supporting, and contiguous to said kitchen electric appliance, and a sleeve of a predetermined size, including a second instance of a noise reflecting material, one or more layers of at least one noise absorbing material, one closed end, and one open end, so that said one open end slides over said kitchen electric appliance and is contiguous to said base. Said noise is effectively abated by reverberating between said first instance of said noise reflecting material and said second instance of said noise reflecting material and is attenuated by said one or more layers of said at least one noise absorbing material.

A system for abating noise emanating from a kitchen electric appliance includes a base of a predetermined size, comprising a first instance of a noise reflecting material, so that said base is disposed underneath, supporting, and contiguous to said kitchen electric appliance, and a sleeve of a predetermined size, including a second instance of a noise reflecting material, one or more layers of at least one noise absorbing material, one closed end, and one open end, so that said one open end slides over said kitchen electric appliance and is contiguous to said base. Said noise is effectively abated by reverberating between said first instance of said noise reflecting material and said second instance of said noise reflecting material and is attenuated by said one or more layers of said at least one noise absorbing material.

An exemplary embodiment of the present invention provides an anisotropic medium for full transmission of obliquely incident elastic waves considering a longitudinal wave and a shear wave by using an anisotropic medium designed to fully transmit elastic waves in a desired mode when elastic waves are obliquely incident to a boundary of different media. The anisotropic medium for fully transmitting an obliquely incident elastic wave according to an exemplary embodiment of the present invention includes: an incident medium to which an incident elastic wave including a longitudinal wave and a shear wave, and being obliquely incident with a predetermined incidence angle, is incident and reflected; a transmission medium to which a transmitting elastic wave including a longitudinal wave and a shear wave is transmitted; and an anisotropic medium, installed between the incident medium and the transmission medium, for blocking reflection of a predetermined reflecting elastic wave as a predetermined full transmission condition is satisfied, and fully transmitting a transmitting elastic wave in a predetermined type of full transmission, wherein the full transmission condition includes a phase matching condition based on a wavenumber relationship of an eigenmode in the anisotropic medium, and a polarization matching condition based on a relationship between a polarization vector and an amplitude of the eigenmode.

Provided are acoustic obstruction prevention equipment for preventing acoustic obstruction by appropriately designing a surface structure of elemental surfaces that surround a space or a surface structure of an acoustic diffuser, and a design method thereof.

A plurality of elemental surfaces that form wall surfaces, a ceiling surface, or a floor surface which surround a space are provided. An angle mutually formed by the elemental surfaces is nα (n is a natural number), and acoustic obstruction is prevented by reflection between the elemental surfaces. φ=(1+sqrt(5))/2, α=360°*1/(1+φ). This technique may be used for a plurality of other elemental surfaces that form an acoustic diffuser disposed in a space. Furthermore, the acoustic diffuser may also be formed by rotating and disposing a plurality of units at the above-described angle multiple times.