Acoustic Properties of Multilayered Structures

Design of microperforated nanofibrous membrane coated nonwoven structure for acoustic applications

“…It could be attributed to the randomness of the membrane resonance effect. As shown in the illustrations in the upper left corner of the figures 4(b)-(d), there was a significant decrease in air permeability when the nonwovens fabric was coated by the microperforated nanofibrous membrane, and thus improved the sound absorbing properties of the structure [17,34]. The fibers on the surface were all in nanometer size, which possessed higher surface area and thus resulted in an increase in friction and more sound energy was consumed.…”

Trend of Sound Absorption Research: A Bibliometric Analysis

“…The second type is known as "open pores", which entails the continuous contact channel with its external medium. Open pores are important for sound absorption [52], permeability [53], and tortuosity [54]. Generally, the general pore ratio is embedded in the sound absorption coefficient [55].…”

Optimum Design of Multi-layered Micro-perforated Panel Sound Absorbers in Combination with Porous Materials in an Arbitrary Frequency Range

“…Hence the use of a Micro perforated panel (MPP) as a strength sound absorber in front of the porous absorber was considered by the researchers [16][17][18][19].…”

“…The disadvantage of this type of sound absorber is the narrow frequency range of absorption. Due to an increase in the frequency range of absorption, some suggestions have been proposed such as the use of multilayered MPPs in succession [23][24][25][26][27] and the use of porous material behind the MPP [16][17][18][19].…”