Acoustic properties of the absorption silencers with a micro-perforated channel in the air-flow

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 ducted. The main objective of the paper is to compare the influence of testing facilities on the measured aeroacoustic performance of tested prototype silencers under an airflow between 4 and 12 m/s. This standard specifies the methods of ISO 7235 for determining the sound power level of the flow noise generated by silencers, the total pressure of silencers, and the insertion loss of silencers with and without airflow by using the substitute object. In this work, we focused on the correlation between the size of the hole in the studied silencers and its acoustic parameters, and also its relation to the insertion loss of silencers.