Micro-perforated panels (MPPs) are known as thin sheets. There are perforated thickness-through hole with sized in the sub-millimetre range. With holes on such a small scale, the panels alone can provide high acoustic resistance and low acoustic reactance, conducive to effective sound absorption. Micro-perforated liners can be useful for attenuation in the low-frequency noise in …
Tag: insertion loss
Sound insulation performance of cube-shaped enclosure
The subject of the research described in the article are the sound insulating properties of a cube-shaped enclosures, the walls of which are made of plates of homogeneous materials and two-layer baffles. As an enclosure for an omnidirectional sound source imitating a noisy machine or device, a prototype test stand for testing the acoustic properties …
Design of the Test Facility for the Measurement of Noise Silencers
In the paper, a description of the test facility designed and implemented for noise silencers according to the methodology specified in the PN-EN ISO 7235 standard is presented. It is possible to measure the insertion loss, flow noise, and pressure loss on the test stand. In particular, the following issues were presented: noise protection in …
Correlation Between the Shape of Substitution Ducts and Insertion Loss of Silencers
Silencers are typical devices used for the reduction of noise in ventilation systems, which can be found in almost all industrial, service or residential installations. Determination of acoustic parameters for specific HVAC devices, like silencers, is within the scope of specialised laboratories. With the silencers, two main parameters should be taken care of: the first …
Experimental Tests of the Acoustic Properties of Sound-Absorbing Linings and Cores of Layered Baffles
The article presents the results of research on the acoustic properties of materials used as sound- absorbing linings and cores in baffles of anti-noise protection. Using an impedance tube the spectral characteristics of the normal incidence sound absorption and sound transmission loss indices of 12 specimens of mineral wool with different density and thickness were …