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2. Blackout (fabric) - Wikipedia

   en.wikipedia.org/wiki/Blackout_(fabric)

   The process of manufacturing blackout was invented by Baltimore-based Rockland Industries, [2] and involves coating a fabric with layers of foam, or 'passes'. A '2-pass' blackout is produced by applying two passes of foam to a fabric – first, a black layer is applied to the fabric, then a white or light-colored layer is applied on top of the black.

3. Noise reduction coefficient - Wikipedia

   en.wikipedia.org/wiki/Noise_reduction_coefficient

   The noise reduction coefficient (commonly abbreviated NRC) is a single number value ranging from 0.0 to 1.0 that describes the average sound absorption performance of a material. An NRC of 0.0 indicates the object does not attenuate mid-frequency sounds, but rather reflects sound energy.

4. Sound attenuator - Wikipedia

   en.wikipedia.org/wiki/Sound_attenuator

   A sound attenuator, or duct silencer, sound trap, or muffler, is a noise control acoustical treatment of Heating Ventilating and Air-Conditioning (HVAC) ductwork designed to reduce transmission of noise through the ductwork, either from equipment into occupied spaces in a building, or between occupied spaces.

5. Sound transmission class - Wikipedia

   en.wikipedia.org/wiki/Sound_transmission_class

   A 0.1% open area will reduce the transmission loss from 40 dB to 30 dB, which is typical of walls where caulking has not been applied effectively [26] Partitions that are inadequately sealed and contain back-to-back electrical boxes, untreated recessed lighting and unsealed pipes offer flanking paths for sound and significant leakage.

6. Acoustic liner - Wikipedia

   en.wikipedia.org/wiki/Acoustic_liner

   The lower half of a liner features dedicated internal slots to allow liquid drainage in order to prevent ice formation or fire hazards. From an acoustic perspective, this implies that the upper acoustic panel is a locally reacting liner, whereas the lower one is a non-locally reacting liner. [1]

7. Noise control - Wikipedia

   en.wikipedia.org/wiki/Noise_control

   Acoustic liners at the intake of a jet engine A composite sandwich acoustic liner (A) with perforate face-sheet (B) honeycomb core (C) and back-skin (D) Aircraft engines, typically turbofans, use acoustic liners to damp engine noise. Liners are applied on the internal walls of the engine nacelle, both in the intake and by-pass ducts, and use ...