Abstract: Provided is a range hood that is small, that can reliably provide the flow path for waste smoke, that has high soundproof performance, and that allows oil stains and the like to be easily removed. The range hood includes: a suction portion that has a suction opening and that sucks air from below in a vertical direction; a connection opening connected to the suction portion; a duct portion that conveys air sucked from the connection opening and discharges the air from a discharge opening to an outside; an air blowing mechanism that is disposed in the duct portion and that moves air in the duct portion to the discharge opening; and a flow regulation plate that is disposed in the suction opening of the suction portion or is disposed so as to cover a part of the suction opening. A distance between the suction portion and the flow regulation plate is 110 mm or smaller.

Abstract: Provided is an air passage type silencer that can reduce pressure loss even in a case where the flow rate of a gas flowing in the air passage type silencer is high. An air passage type silencer includes an inlet-side ventilation pipe, an expansion portion that communicates with the inlet-side ventilation pipe and of which a cross-sectional area is larger than a cross-sectional area of the inlet-side ventilation pipe, and an outlet-side ventilation pipe that communicates with the expansion portion and of which a cross-sectional area is smaller than the cross-sectional area of the expansion portion.

Abstract: In a soundproof structure body including a tubular tube body having an opening portion, and a resonance type soundproof structure, in which a phase difference ?, at an upstream of the resonance type soundproof structure, between a reflected wave in the resonance type soundproof structure and a reflected wave of a transmitted wave transmitted through the resonance type soundproof structure and reflected by the opening portion satisfies Inequation |???|??/3 with respect to a resonance frequency of the resonance type soundproof structure. This soundproof structure body can effectively offset a reflected wave from a resonance type soundproof structure body by opening end reflection by appropriately specifying positions of the resonance type soundproof structure and the opening end portion of a duct, a tube line, or the like to improve an absorbance of a single resonance type soundproof structure.

Abstract: An object is to provide a ventilation system that can suppress generation of a pressure loss and wind noise in a silencer. The ventilation system of the present invention has the silencer disposed at an intermediate position of a ventilation path. In a housing of the silencer, an in-housing ventilation path extending from an inlet opening to an outlet opening is surrounded by a sound absorbing member. The ventilation path has a first ventilation path that is adjacent to the inlet opening and that is continuous to the in-housing ventilation path and a second ventilation path that is adjacent to the outlet opening and that is continuous to the in-housing ventilation path. The farther from the in-housing ventilation path, the smaller a size of a cross section of at least one ventilation path of the first ventilation path or the second ventilation path.

Abstract: Provided is a ventilation system in which a silencer has a compact structure, a silencing property is ensured, and a pressure loss in the silencer is suppressed. The ventilation system of the present invention has a silencer disposed at an intermediate position of a ventilation path. In the silencer, a sound absorbing member surrounds a housing in which an in-housing ventilation path extending from an inlet opening to an outlet opening is provided. In addition, an upstream tube body that forms an upstream ventilation path on an upstream side of an inlet opening, a downstream tube body that forms a downstream ventilation path on a downstream side of an outlet opening, a tubular first connecting portion that is connected to the upstream tube body and that links the upstream ventilation path and the inlet opening to each other, and a tubular second connecting portion that is connected to the downstream tube body and that links the downstream ventilation path and the outlet opening to each other are provided.

Abstract: Provided is an air passage type silencer that can drain water from the inside of an expansion portion and that can suppress generation of a wind noise.

Abstract: An axial fan that includes a casing having an inner space that penetrates in one direction, and a rotor blade disposed in the inner space of the casing, and a silencer that is disposed at a position connected to the inner space of the axial fan are provided, in which the axial fan has a sound pressure distribution having a position at which a sound pressure is high and a position at which the sound pressure is low in a circumferential direction in the inner space during driving, and the silencer is disposed at the position of the axial fan in the circumferential direction at which the sound pressure is high and is not disposed at the position at which the sound pressure is low.

Abstract: A silencer for a ventilation passage effectively deadens sound having a broad frequency band while having a compact structure. A silencer for a ventilation passage according to an embodiment of the present invention is a silencer for a ventilation passage that includes a housing and deadens sound in a ventilation passage, and an internal space of the housing forms a part of the ventilation passage. The silencer for a ventilation passage includes an inlet opening that is positioned on one end side of a part of the ventilation passage in the housing, an outlet opening that is positioned on the other end side of a part of the ventilation passage in the housing, a sound absorbing member that is housed in the housing, and a vibration portion that is provided on the housing and reduces sound passing through the ventilation passage.

Abstract: To provide an air passage type silencer that can suppress generation of a wind noise, that has a high sound attenuation effect in a low-frequency band, and that has high air passage performance.

Abstract: A blower with a silencer has the blower including an axial fan including a casing, a motor attached to the casing, and a rotor having a shaft portion attached to the motor and rotated and a blade formed to protrude to an outer side of the shaft portion in a radial direction, and a silencer attached to the casing, in which the silencer includes a resonator that selectively silences a dominant sound generated by the axial fan, the silencer is disposed at a position in which at least a part of the silencer overlaps with the shaft portion, as viewed from a rotation axis direction of the rotor, and in a case in which, in a cross section perpendicular to a rotation axis of the rotor, a circle around the rotation axis, which has a radius of a line connecting the rotation axis and a point of a most distal end of the blade, is defined as a rotation region, an area of the silencer in the cross section perpendicular to the rotation axis is smaller than an area of the rotation region.

Abstract: To effectively reduce a low-frequency noise resulting from vibration of a peripheral wall of a ventilation path. The present invention provides a ventilation path with a soundproof structure including a ventilation path that includes an open end and a soundproof structure against a sound emitted from the ventilation path.

Abstract: An acoustic system includes a duct that has a function of causing a fluid to flow therein and has a tubular shape, an internal sound source that is disposed inside the duct on an upstream side or at an outer peripheral portion of the duct, which communicates with an inside of the duct on the upstream side, or an external sound source that is on an outside from an end portion of the duct, and a membrane-shaped member that is formed as a part of a wall of the duct and vibrates in response to sound. A structure including the membrane-shaped member and a rear surface closed space thereof causes acoustic resonance to occur, transmits the acoustic resonance from the sound source into the duct, and suppresses sound radiated from the other end portion of the duct on a downstream side. The external sound source is at a distance within a wavelength at a frequency of the acoustic resonance on the outside from the end portion of the duct.

Abstract: To provide an air passage type silencer and an acoustic impedance change structure of which the absorbance is high, that suppresses generation of a wind noise, and that has a high sound attenuation effect in a low-frequency band. Provided is an acoustic impedance change structure through which a sound propagates, the acoustic impedance change structure including at least in this order: a first impedance matching region that is connected to an inlet portion and in which an acoustic impedance gradually decreases; an acoustic impedance constancy region; and an outlet portion, in which Zcham<Zin and Zcham<Zout are satisfied, where Zin is an acoustic impedance in the inlet portion, Zcham is an acoustic impedance in the acoustic impedance constancy region, and Zout is an acoustic impedance in the outlet portion, and a first terminal structure acoustically connected to the acoustic impedance constancy region is provided.

Abstract: To provide a silencing structure and a silencing system having a high sound absorbance in a low frequency region. A silencing structure that is installed in a tubular member, the silencing structure includes a cavity portion, an opening portion through which the cavity portion communicates with the tubular member, and a closing portion that closes the cavity portion at a position facing the opening portion, in which a cross-sectional area of the cavity portion on a side of the opening portion is larger than a cross-sectional area of the cavity portion on a side of the closing portion.

Abstract: An object is to provide a silencing system that can achieve both high ventilation performance and high soundproof performance, can silence a plurality of pieces of resonant sound, and has high general-purpose properties since the silencing system does not need to be designed according to a tubular member. The silencing system includes one or more silencers that are disposed in a tubular member provided to penetrate a wall separating two spaces, and satisfies “0<Re[Bn]<1” and “Im[Bn]>0” in a case where a standardized effective modulus of elasticity in an interior space of the tubular member in which the silencers are disposed is denoted by Bn.

Abstract: An object is to provide a silencing system that includes a silencer disposed in a ventilation sleeve, can suppress the generation of negative pressure in the interior, and can prevent a door or the like of an interior entrance from being difficult to open. The silencing system includes one or more silencers that are disposed in a ventilation sleeve provided to penetrate a wall separating two spaces, and “?A>10C?(0.1/P)×TL” is satisfied in a case where a gap equivalent area of the ventilation sleeve in which the silencer is installed is denoted by ?A and a normalized sound transmission loss in an octave band in which a first resonant frequency of the ventilation sleeve is present is denoted by TL. C denotes a constant determined by a measurement system in a case where there is no silencer and P denotes a transmission efficiency coefficient.

Abstract: A fan, and a silencer that silences a sound generated by the fan are provided, in which the silencer has a resonance characteristic, the silencer is disposed at a position connected to a sound field space of the sound generated by the fan, and a sum of an absorbance and a reflectivity of the silencer at a resonance frequency is 10% to 43% and a standardized half-width of the silencer is more than 0.05 and 0.25 or less.

Abstract: Provided is a soundproof structure that is small and light and can reduce a noise with a high specific frequency of a sound source at a plurality of frequencies at the same time.

Abstract: Provided is a soundproof structure that is small and light and can reduce a noise with a high specific frequency of a sound source at a plurality of frequencies at the same time.

Abstract: Provided is a soundproof structure that is small and light and can reduce noise with a high natural frequency of a sound source at a plurality of frequencies at the same time. The soundproof structure according to the embodiment of the present invention includes a plurality of membrane-like members that are overlapped to be spaced from each other, a support that is made of a rigid body and supports each of the plurality of membrane-like members so as to perform membrane vibration, an inter-membrane space that is sandwiched between two adjacent membrane-like members among the plurality of membrane-like members, and a rear surface space that is formed between one membrane-like member at one end of the support in the support among the plurality of membrane-like members and the one end of the support, in which each of the plurality of membrane-like members absorbs a sound by performing the membrane vibration in a state where the one end of the support is closed.