Provided are acoustic articles, and related methods, that include a porous layer and heterogeneous filler received in the porous layer. The heterogeneous filler can include clay, diatomaceous earth, graphite, glass bubbles, polymeric filler, non-layered silicate, plant-based filler, or a combination thereof, and can have a median particle size of from 1 micrometer to 1000 micrometers and a specific surface area of from 0.1 m.sup.2/g to 800 m.sup.2/g. The acoustic article can have an overall flow resistance of from 100 MKS Rayls to 8000 MKS Rayls. The acoustic articles can serve as acoustic absorbers, vibration dampers, and/or acoustic and thermal insulators.

Provided are acoustic articles, and related methods, that include a porous layer and heterogeneous filler received in the porous layer. The heterogeneous filler can include clay, diatomaceous earth, graphite, glass bubbles, polymeric filler, non-layered silicate, plant-based filler, or a combination thereof, and can have a median particle size of from 1 micrometer to 1000 micrometers and a specific surface area of from 0.1 m.sup.2/g to 800 m.sup.2/g. The acoustic article can have an overall flow resistance of from 100 MKS Rayls to 8000 MKS Rayls. The acoustic articles can serve as acoustic absorbers, vibration dampers, and/or acoustic and thermal insulators.

A fluid system can have a water hammer arrestor including a resilient insert having an outer surface. The resilient insert can be operable to dampen a pressure spike in the fluid that exceeds a static pressure range, providing effective water hammer arrestment that without the resilient insert, would have occurred in a flowing fluid with the pressure spike. The static pressure range can be up to about 100 psig.

A fluid system can have a water hammer arrestor including a resilient insert having an outer surface. The resilient insert can be operable to dampen a pressure spike in the fluid that exceeds a static pressure range, providing effective water hammer arrestment that without the resilient insert, would have occurred in a flowing fluid with the pressure spike. The static pressure range can be up to about 100 psig.

Occlusion devices, earpiece devices and methods of forming occlusion devices are provided. An occlusion device is configured to occlude an ear canal, but other biological and non-biological conduits or chambers can be occluded using the devices and methods herein. The occlusion device includes an insertion element and at least one occluding member or element (which can be expandable) disposed on the insertion element. The occluding member is configured to receive a medium via the insertion element and is configured to expand, responsive to the medium, to contact the ear canal. Alternatively, the occluding member is made of a non-Newtonian fluid and can be enclosed by a balloon or not. Physical parameters of the occlusion device are selected to produce a predetermined sound attenuation characteristic over a frequency band. Use of a non-Newtonian fluid provides additional options or variables in customizing or designing a predetermined sound attenuation characteristic.

Occlusion devices, earpiece devices and methods of forming occlusion devices are provided. An occlusion device is configured to occlude an ear canal, but other biological and non-biological conduits or chambers can be occluded using the devices and methods herein. The occlusion device includes an insertion element and at least one occluding member or element (which can be expandable) disposed on the insertion element. The occluding member is configured to receive a medium via the insertion element and is configured to expand, responsive to the medium, to contact the ear canal. Alternatively, the occluding member is made of a non-Newtonian fluid and can be enclosed by a balloon or not. Physical parameters of the occlusion device are selected to produce a predetermined sound attenuation characteristic over a frequency band. Use of a non-Newtonian fluid provides additional options or variables in customizing or designing a predetermined sound attenuation characteristic.

A noise damper for reducing noise from a vibrating element which vibrates at a vibrational frequency, wherein the noise damper is configured to be in contact with the vibrating element such that when the noise damper is in contact with the vibrating element a noise amplitude at a point in a surrounding of the vibrating element is given by an attenuation factor times the noise amplitude at the point in the surrounding when the noise damper is disconnected from the vibrating element, the noise damper comprising: a polymer matrix, the polymer matrix being in a solid phase and forming a shape; a plurality of hollow particles dispersed in the polymer matrix, each hollow particle having a shell encapsulating a gas filled cavity, each hollow particle having a hollow particle size, and the plurality of hollow particles being dispersed at a hollow particle concentration in the polymer matrix; wherein the hollow particle size and the hollow particle concentration are configured to set the attenuation factor below an attenuation factor threshold at the vibrational frequency of the vibrating element, the hollow particle size being in a range wherein the largest dimension is between 20 μm and 2000 μm.

A noise damper for reducing noise from a vibrating element which vibrates at a vibrational frequency, wherein the noise damper is configured to be in contact with the vibrating element such that when the noise damper is in contact with the vibrating element a noise amplitude at a point in a surrounding of the vibrating element is given by an attenuation factor times the noise amplitude at the point in the surrounding when the noise damper is disconnected from the vibrating element, the noise damper comprising: a polymer matrix, the polymer matrix being in a solid phase and forming a shape; a plurality of hollow particles dispersed in the polymer matrix, each hollow particle having a shell encapsulating a gas filled cavity, each hollow particle having a hollow particle size, and the plurality of hollow particles being dispersed at a hollow particle concentration in the polymer matrix; wherein the hollow particle size and the hollow particle concentration are configured to set the attenuation factor below an attenuation factor threshold at the vibrational frequency of the vibrating element, the hollow particle size being in a range wherein the largest dimension is between 20 μm and 2000 μm.

A porous sound absorbing material having an average cell size of 100 to 600 μm and an apparent density of 40 to 140 kg/m.sup.3. A sound absorption method using this porous sound absorbing material.

An acoustic element includes a nanovoided polymer layer having a first nanovoid topology in an unactuated state and a second nanovoid topology different than the first nanovoid topology in an actuated state. Capacitive actuation of the nanovoided polymer layer, for instance, can be used to reversibly control the size and shape of the nanovoids within the polymer layer and hence tune its sound damping characteristics or sound transduction behavior, e.g., during operation of the acoustic element. An acoustic element may be configured for passive or active sound attenuation. Various other apparatuses, systems, materials, and methods are also disclosed.