81 results about "Acoustical resistance" patented technology

A protective acoustic cover assembly including a metal foil with perforations, and a treatment on one or more surfaces of said metal foil. The treatment is a hydrophobic or oleophobic treatment, or both. The protective acoustic cover assembly has an average specific acoustic resistance of less than about 11 Rayls MKS from 250-300 Hz, an average specific acoustic reactance magnitude of less than about 1 Rayls MKS from 250-300 Hz, and an instantaneous water entry pressure value of greater than about 11 cm. The perforations of the metal foil preferably have an average maximum pore size of less than about 150 micrometers. The protective acoustic cover assembly further includes an adhesive mounting system, and the preferred metal foil is nickel.

The invention relates to a composite sound absorbing device with a built-in resonant cavity. The device comprises a perforated plate with a plurality of first holes, a back plate and a side plate, wherein a sealed cavity is formed by the perforated plate, the back plate and the side plate. The device is characterized in that at least one or more resonant cavities are placed in the sealed cavity; the resonant cavity is provided with at least one or more second holes; at least one of the second holes is communicated with the sealed cavity; the volume V of the resonant cavity is equal to 10mm3-1*1,010mm3, and the thickness of the wall of the cavity is 0.05 to 10 mm; and the aperture d, of the second hole on the cavity is equal to 0.05 to 100 mm, and the perforated percentage sigma, is 0.01 to 30 percent. The device forms acoustic scattering in the sealed cavity through the resonant cavity; and the second hole increases the acoustic resistance and the multi-cavity coupling resonance. The device has a flexible design and contributes to improving sound absorbing effect and expanding the sound absorbing frequency band.

The invention discloses a preparation method of a high-sound-absorption ultralight high-strength GMT composite board. According to the preparation method, a microsphere foaming agent is introduced into a GMT felt screen through an impregnation technology in the back pass of an existing light GMT dry combing felt forming technology, the expansibility of the board is adjusted by changing a supporting method of connection of lattice points among reinforced fibers and combining the expanding characteristic of the microsphere foaming agent, the obtained board can be expanded in secondary forming, and then the thickness reaches 5-10 times that of the original thickness; pressing fixing is conducted as needed by adjusting the expanded compression ratio according to the product performance requirements, and automotive internal and external ornament products with different strength, rigidity and sound resistance characteristics are obtained. Therefore, the problems that in a traditional light GMT product, further ultra-lightweight design is difficult, the impregnated air volume is insufficient, and the design freedom degree and the NVH performance of the product are far behind of those of foreign imported products are effectively solved.

An aircraft nacelle includes an air intake that makes it possible to channel the air in a pipe in the direction of a pipe of a power plant that is arranged in the extension of the pipe, whereby the pipe of the air intake includes at least one panel that integrates an acoustic treatment with an acoustically resistive porous layer that is in contact with the aerodynamic stream that enters into the nacelle, at least one alveolar structure, and a reflective or impermeable layer that forms the rear surface of the panel, a flange that ensures the connection between the air intake and the power plant including at least one wing that is connected to the air intake by a number of connecting elements, characterized in that some of the connecting elements have axes that are secant with the edge of the panel that delimits the pipe of the air intake.

A system for dissipating sound shock waves within a vehicle tire includes a wheel upon which a tire is mounted to create an internal air chamber defined by the wheel and the tire. A flow-resistant barrier is coupled to the wheel or the tire and defines an air cavity within the internal air chamber. The barrier comprises a material that provides an acoustical resistance to sound shock waves passing therethrough. The air cavity defined by the barrier has a volume such that air within the cavity offers relatively small impedance to the passage of shock waves through the barrier and into the air cavity. The barrier also can produce frictional heat when displaced by a shock wave, thereby converting energy of the shock wave to heat to reduce noise associated therewith.

A MEMS microphone, which comprises a substrate, a first vibrating diaphragm and a second vibrating diaphragm is provided. A sealed cavity is formed between the first vibrating diaphragm and the second vibrating diaphragm. A back electrode unit is located in the sealed cavity, forms a capacitor structure with the first vibrating diaphragm and with the second vibrating diaphragm respectively, and is provided with a plurality of through holes that penetrate through two sides thereof. The sealed cavity is filled with a gas whose viscosity coefficient is smaller than that of air. According to the MEMS microphone disclosed by the present invention, by filling the sealed cavity with a gas whose viscosity coefficient is smaller than that of air, the acoustic resistance when the two vibrating diaphragms move relative to the back electrode can be reduced greatly, thereby reducing the noise of the microphone. Meanwhile, by the use of a gas with a low viscosity coefficient for filling, the pressure in the sealed cavity is consistent with the pressure of an external environment, thereby avoiding the problem of vibrating diaphragm deflection caused by pressure difference and ensuring the performances of the microphone.

The invention relates to an anti-spallation structure processed by laser shock processing, metal target material is titanium alloy, aluminium alloy or stainless steel; wherein, the back of the metal target material is coated with a protection layer made of a material which has an acoustic resistance close to the acoustic resistance of the metal target material, namely a single-layer or multiple-layer aluminium foil tapes with the thickness between 0.2 and 0.5 millimetres; when spallation occurs in a wave-absorbing layer of a reflection area and the reflection area overlaps on the area to be reinforced next time for 50%, the wave-absorbing layer needs to be changed. The technical proposal of the invention has excellent effects on thin wall structure processed by laser shock processing or parts which have thick sections but are close to the inner wall.

Systems, apparatus and methods are discussed for controlling resonance in in-the-ear headphones. Resonance effects resulting from wave reflection and superposition can occur in the cavity formed by the port tube of an earbud and the wearer's ear canal. In this invention, acoustically resistive structures are provided to create sound diffusion in the cavity. In one embodiment, a spring coil with several adjustable parameters is inserted into the port tube. In another embodiment, a pattern of grooves is carved into the inner surface of the port tube. Porous filters can also be used in conjunction with both of the embodiments described above. The result of providing the resistive structures in an earbud is a flattened cavity frequency response and improved sound quality.

A method for manufacturing an acoustic absorption structure including an acoustically resistive layer, a cellular structure, a reflective layer and a plurality of acoustic elements positioned in cavities produced in the cellular structure. This method comprises steps of depositing fiber plies on a contact surface of the cellular structure, fitting a flexible jacket which covers a stack composed of the acoustically resistive layer, the cellular structure and the fiber plies, which is tightly linked with the deposition surface all around the stack, consolidating the fiber plies to form the reflective layer and the fixing thereof on the cellular structure, with a caul plate being inserted between the fiber plies and the flexible jacket during the consolidation step.

A method for producing an acoustic absorption structure comprising an acoustically resistive structure, an alveolar structure, a reflective layer and a plurality of acoustic elements positioned in the alveolar structure, against the acoustically resistive structure, the method comprising forming a skin forming enclosures of the acoustic elements by depositing a resin on a mold having a base on which are positioned projecting forms shaped like the cavities delimited by the enclosures of the acoustic elements, placing the mold supporting the resin together with the alveolar structure, the resin being intercalated between the mold and the alveolar structure, polymerizing the resin to simultaneously obtain a hardening of the skin and also the joint between the skin and the alveolar structure, and fitting the acoustically resistive structure and the reflective layer.

The invention discloses a rotary-scanning online ultrasonic detection method for cylinders. To-be-detected cylinders are placed in designated positions by a mechanical moving part; positions of transverse and longitudinal detection probes are adjusted, and longitudinal probe detects point-like and transverse surface-like defects, and the transverse probe detects point-like and longitudinal surface-like defects; ultrasonic frequency ranges are selected according to different cylinders; the cylinders are rotated for detection; positions and degrees of the defects are judged according to echo signals. With the adoption of the method, the detection efficiency is improved, and the cylinders made of different materials can be detected through change of acoustic resistance models and positions of sensors.

In one embodiment, an apparatus includes a graphic display panel and a speaker. The panel has a display layer for displaying images and defines a plurality of holes penetrating at least the display layer. The speaker includes a diaphragm arranged substantially parallel to the display layer. Sound from the speaker diaphragm is directed out of the host device through the holes. Speakers can be electret or piezoelectric speakers for thinness. There may be holes on the opposite side of the host device case for a dipole pattern that is directional and gives acoustic privacy to the user, or a rear acoustic cavity for a monopole pattern that is wider Disperse the sound. One illustrated embodiment is selectable between monopole and dipole. The size and total area of ​​the apertures determine the acoustic resistance, so a method for determining them from the physical parameters of the display panel is described.

The invention discloses an assessment method for the anti-pollution capability of a dustproof net of a mobile phone and belongs to the technical field of engineering materials. The assessment method comprises the following steps of firstly, establishing an assessment scheme, i.e., establishing a dustproof net parameter assessment scheme by analyzing structural parameters and coating parameters of the dustproof net of the mobile phone to be assessed; determining an experiment control group and the quantity of samples required by the experiment according to specific characteristic parameters of samples to be assessed; secondly, implementing pollution simulation experiments including an oil mist evaporation and deposition experiment and a grease coating and adhering experiment; finally, assessing the anti-pollution capability through acoustic resistance detection. According to the assessment method, on the basis of a pollutant deposition principle and aiming at specific parameters of the dustproof net, an assessment system for the anti-pollution capability of the dustproof net can be effectively and accurately established.

An escape system for a sinking car and an ultrasonic component thereof are illustrated. In the present disclosure, an ultrasonic signal transmitting unit capable of emitting ultrasonic is installed on the car. When the car falls into the water, based upon an acoustic resistance concept which the ultrasonic propagated in air collides and transmits into the water, a difference between a reflection or transmittance rate of the ultrasonic and a corresponding set value can be calculated, or alternatively, a difference between a reflection time deviation or a reflection distance of the ultrasonic and a corresponding set value can be calculated. Therefore, a warning signal indicating that the car falls into the water can be fast sent, and this makes sure that the rescue opportunity which the car falls into the water can be grasped to decrease the damage or death of the user.

The invention relates to a composite sound absorbing device with a built-in resonant cavity. The device comprises a perforated plate with a plurality of first holes, a back plate and a side plate, wherein a sealed cavity is formed by the perforated plate, the back plate and the side plate. The device is characterized in that at least one or more resonant cavities are placed in the sealed cavity; the resonant cavity is provided with at least one or more second holes; at least one of the second holes is communicated with the sealed cavity; the volume V of the resonant cavity is equal to 10mm3-1*1,010mm3, and the thickness of the wall of the cavity is 0.05 to 10 mm; and the aperture d, of the second hole on the cavity is equal to 0.05 to 100 mm, and the perforated percentage sigma, is 0.01 to 30 percent. The device forms acoustic scattering in the sealed cavity through the resonant cavity; and the second hole increases the acoustic resistance and the multi-cavity coupling resonance. The device has a flexible design and contributes to improving sound absorbing effect and expanding the sound absorbing frequency band.

The embodiment of the invention relates to the field of noise protection, and discloses earmuffs and a noise reduction method by earmuffs. In the invention, the earmuffs comprise at least one cover, asound collecting module, an acoustic foam, a compressing device and a processing unit. The sound collecting module collects the environment noise and obtains the noise amplitude value of the environment noise. The acoustic foam creates acoustic resistance in the cover. The compressing device is used for compressing the acoustic foam in the cover to change the sound resistance in the cover. The processing unit is separately electrically connected with the compressing device and the sound collecting module and pre-stores the preset amplitude value of the environment noise. The processing unit acquires the noise amplitude value obtained by the sound collecting module and calculates a desired resistance value of the acoustic resistance required for reducing the noise amplitude value to the preset amplitude value according to the noise amplitude value. The processing unit further controls the compression amount when the compressing device compresses the acoustic foam according to the desired resistance value. Thus, the acoustic resistance is increased when the acoustic foam is compressed to reduce the environment noise to the preset amplitude value, so that the noise is effectively reduced to reduce the harm to human ears.

An acoustic filter including a valve system with acoustic valves arranged in a sound passage for controlling the acoustic resistance of respective apertures based on a control signal for selecting an attenuation of a sound pressure level of transmitted sound compared to that of received sound. The acoustic filter is adapted to provide the selection of the attenuation from a sequence of predetermined attenuations based on a selection of the control signal. Each attenuation in the sequence corresponds to acoustic valves providing the apertures with a respective predetermined acoustic resistance, wherein the acoustic resistances of subsequent attenuations in the sequence are adapted to correspond with a linear increase or decrease in the attenuation of the sound in decibels.