Methods and systems are provided for adjusting a position of an exhaust valve that regulates engine exhaust noise. In one example, the position of the exhaust valve is adjusted according to a distance between a first vehicle and a second vehicle. The exhaust valve may be adjusted to reduce an exhaust noise level when the distance between the first vehicle and the second vehicle is less than a threshold distance.

The present disclosure relates to a hairdryer and, more specifically, to a hairdryer wherein a ratio between dimensions of fan unit components is appropriately changed to stabilize the flow of air introduced into a fan unit and suppress occurrence of turbulence so that internal flow efficiency can be increased and the noise can be decreased.

A sound suppressor for use in firearms, internal combustion engines, and numerous other sound-generating devices includes a structure having a plurality of ports, openings, or orifices which function as whistles and which suppress sound from a source of the sound using destructive interference. A combination of varying distances between components is configured for delaying the wave from one port or whistle to the next, so that the whistles are partially out of phase with respect to time, and placing the orifices of the whistles a certain distance apart to compensate for the remaining phase difference in order to create the desired destructive interference.

A noise reduction assembly includes an outer frame and a partition plate. An accommodating cavity is arranged in the outer frame; the partition plate is arranged in the accommodating cavity, and the partition plate and the outer frame form a noise reduction channel, the noise reduction channel includes a first noise reduction section, a second noise reduction section and a third noise reduction section that are communicated in sequence, and the channel cross-sectional areas of the first noise reduction section and the third noise reduction section are both smaller than the channel cross-sectional area of the second noise reduction section. The technical solution of the present application may reduce the noise of a new energy equipment having the noise reduction assembly during operation.

A transducer is provided for emitting and receiving acoustic waves, a method for operating and a method for producing the same. The transducer comprises a casing that forms a cavity. The casing comprises an excitation surface and an emitting surface, which is arranged opposite to the excitation surface. A transducer element is provided at the excitation surface, and an acoustic diffuser is provided at the emitting surface of the casing, wherein a diffusing structure of the acoustic diffuser faces the cavity.

A method for automatically changing the engine exhaust sound in conjunction with the traveling mode implemented by the exhaust system applied to the vehicle may vary the valve opening of an electronic variable valve provided in a first tail pipe of first and second tail pipes of muffler discharging the exhaust gas coming from an engine by a mode recognition logic connected to an engine ECU to the atmosphere, and control the variation of the valve opening with the engine torque and the engine RPM based on a change in an accelerator pedal stroke in any one of a SMART DRIVE MODE-ECO state, a SMART DRIVE MODE-COMFORT state, and a SMART DRIVE MODE-SPORT state, implementing a quiet engine exhaust sound and a sporty engine exhaust sound depending on various vehicle traveling states provided by the SMART DRIVE MODE and increasing vehicle/engine outputs.

A two-stage water-lift and water separation muffler for use with marine electrical generators installed onboard marine vessels. A first stage water-lift muffler has internal tunable sound suppression structure to provide a first stage of exhaust silencing, and a second stage water separator having internal tunable sound suppression structure to provide a second stage of exhaust silencing while separating entrained cooling water from exhaust gases. The combined first stage water-lift muffler and second stage water separator include internal baffling and silencing structure which is easily adaptable to different generator configurations thereby allowing for structural adjustments to the muffler to optimize sound suppression and minimize backpressure for particular generator and/or exhaust conditions.

Aspects are disclosed of a filler for occupying a volume. The filler includes an expandable filler positioned in the volume so that it occupies a percentage of the volume. The expandable filler can permanently expand from a first dimension to a second dimension upon the application of an expansion trigger. The filler also includes an acoustic filler made up of a plurality of acoustically active beads positioned with the expandable filler in the volume so that the acoustic filler can adsorb gas flowing into the volume. Other embodiments are disclosed and claimed.

In a structure for mounting resonators to a duct, the duct including openings is provided with a plurality of duct-side mounting pieces, and the resonators formed separately from the duct and including communication ports coupled to the openings are provided with a plurality of resonator-side mounting pieces that are mounted to the duct-side mounting pieces. Coupling portions of the duct and the resonators are configured to ensure turning the resonators when the resonators are mounted to the duct. On the plurality of duct-side mounting pieces disposed with intervals in a peripheral direction of the coupling portions, mounting surfaces are formed to be opposed to turning directions of the resonators when mounting the resonators to the duct, the resonator-side mounting pieces being abutted against and mounted to the mounting surfaces. Accordingly, it is possible to turn the resonators when mounting them to the duct and improve attachment work.

Provided are: a muffler that can suitably obtain an attenuation effect of a sound wave; and a muffling device including the same. The muffler is installed on a wall surface of a pipe conduit where a gas flows. The muffler includes: a front surface exposed to an inner surface of the pipe conduit; a bottom surface facing the front surface; and a side surface disposed between the front surface and the bottom surface and covering a space between the front surface and the bottom surface. The front surface is formed with a plurality of through-holes, and the number of through-holes arrayed in a gas flow direction is one or two, and the number thereof arrayed in a direction orthogonal to the gas flow direction is 10 or more.