A noise reduction structure for a ventilation treatment device and the ventilation treatment device are provided. The noise reduction structure comprises a first micropore plate; the first micropore plate has a first plate surface and a second plate surface which are opposite to each other, the first plate surface is used for forming a first chamber; the second plate surface is used for forming an air passage such that air in the air passage flows along the second plate surface; the first micropore plate has a plurality of first micro-vias through which the first chamber communicates with the air passage. The noise reduction structure is wide in noise reduction frequency band, may effectively reduce aerodynamic noise in the air passage, and improves the satisfaction degree of a patient using the ventilation treatment device.

The present application discloses a sound absorbing device to be placed in an airflow that is in a first direction. The sound absorbing device includes a housing; a plurality of sound absorbing units disposed in the housing to be passed by the airflow, the plurality of sound absorbing units being arranged in a direction perpendicular to the first direction, any two adjacent sound absorbing units being separated by a gap; and a plurality of supports fixed in the housing. The plurality of sound absorbing units are fixed to the housing through the plurality of supports.

One feature pertains to an acoustic attenuation device. The acoustic attenuation device comprises a fan assembly, the fan assembly including at least one fan module that directs airflow in at least one direction, wherein the at least one fan module includes a top surface and a bottom surface, a plurality of air deflectors mounted to the top surface and the bottom surface of the at least one fan module, wherein the plurality of air deflectors include a plurality of surfaces, and wherein at least one of the plurality of surfaces is an angled surface that redirects the airflow 90-degrees, and acoustic attenuating foam, wherein the acoustic attenuating foam has a two-dimensional (2-D) surface and is applied to interior surfaces of the plurality of surfaces.

A blower unit can include an outer housing, an inlet subassembly, a fan subassembly, an outlet subassembly, and a grommet. The outer housing can have an aperture extend along a first axis between first and second ends. The inlet subassembly can be received in the first end of the aperture. The fan subassembly can be received in the aperture adjacent to the inlet subassembly and include at least one wire. The outlet subassembly can be received in the second end. The grommet can be positioned between at least part of the second end and the outlet subassembly. The at least one wire can extend through the grommet. The grommet can seal against the at least one wire. The grommet can seal between the outer housing and the outlet subassembly.

A head-mountable flow generator is configured to deliver a flow of breathable gas at a continuously positive pressure with respect to ambient air pressure to a patient interface in communication with an entrance to a patient's airways including at least an entrance of the patient's nares, while the patient is sleeping, to ameliorate sleep disordered breathing. The flow generator includes a motor, an impeller assembly and housing that encases the motor and the impeller assembly. The housing is configured to be mounted on the patient's head and comprises an inlet to receive the flow of breathable gas and a pair of opposing outlets to deliver the flow of breathable gas. In addition, the impeller assembly is configured to pressurize the flow of breathable gas received from the inlet, and the housing is configured to convey the pressurized flow of breathable gas through both outlets.

A filter muffler includes a front element, a rear element, and a plurality of damping elements arranged between the front element and the rear element, where the damping elements are arranged radially around a central axis of the filter muffler such that a flow channel is formed between adjacent damping elements, where respective outflow-side ends of the damping elements have a diffuser element which has an outflow-side tapering, and where an angle α between two opposite sides of the diffuser element is selected from a range of 1°≤α≤8°.

A reference microphone for detecting noise is located under a first duct. The noise is in the form of a first plane wave in the first duct. A speaker is located on a top of the first duct. Connected to an upper part of the first duct is a second duct including an error microphone. The first plane wave in the first duct passes through an acoustic path and reaches the second duct. The error microphone detects the sound, and the speaker outputs a second plane wave with an opposite phase for canceling the first plane wave.

Provided is an axial flow blower capable of improving an intake efficiency even when air is introduced from a plurality of suction openings. An axial flow blower includes a housing including an air blowing passage extending from a plurality of suction openings (lateral suction opening and lower suction opening) to an ejection opening, an electric motor, and an air blowing fan that blows air from the plurality of suction openings (lateral suction opening and lower suction opening) toward the ejection opening. An air blowing guide member is provided closer to the plurality of suction openings (lateral suction opening and lower suction opening) than to the air blowing fan, inside of the plurality of suction openings (lateral suction opening and lower suction opening). The air blowing guide member guides air introduced into the air blowing passage from the plurality of suction openings (lateral suction opening and lower suction opening) toward the air blowing fan.

A vehicle heater includes a heater housing (12′), through which heating air to be heated can flow, with a heating air inlet area and with a heating air outlet area. A burner unit is arranged in the heater housing. A combustion air blower (46′) is arranged in the heater housing for delivering combustion air to the burner unit. A heat exchanger unit is arranged in the heater housing (12′). Heating air flowing through the heater housing (12′) can flow around the heat exchanger unit. A combustion air intake muffler (76) is arranged essentially in the heater housing (12′). A muffler housing (78) made in one piece with the heater housing (12′) is associated with the combustion air blower (46′).

A fan section for a gas turbine engine according to an example of the present disclosure includes, among other things, a fan rotor having fan blades, and a plurality of fan exit guide vanes positioned downstream of the fan rotor. The fan rotor is configured to be driven through a gear reduction. A ratio of a number of fan exit guide vanes to a number of fan blades is defined. The fan exit guide vanes are provided with optimized sweep and optimized lean.