Sandwich Absorbers and their Acoustic Properties

Abstract

In spite of existing European and national legislation aimed at noise abatement, public interest and concern about noise are high. The EU Directive 70/157/EEC [15] for setting and controlling environmental noise is aimed at creating less noisy and more pleasant environment for European residents within "Sustainable Development in Europe". The authors are presenting a methodology for measuring selected acoustic descriptors (sound absorption coefficient and sound transmission loss) for acoustic materials, which are currently in process of development. Emphasis is put on sandwich structures of absorbers. Verification results of the proposed methodology are presented.

Analysis and Research on the Use of Bulk Recycled Materials for Sound Insulation Applications

“…The following acoustic quantities were evaluated and measured to evaluate the acoustic properties of the materials: sound absorption coefficient α (dimensionless); sound reduction index R (dB) [38].…”

“…The sound absorption coefficient is used to evaluate the sound absorption efficiency of materials. It is a dimensionless quantity defined as the ratio of the intensity of the sound wave absorbed by the given material (I) to the sound intensity of the wave reaching the given material (I 0 ) [38]:…”

“…The effect factor in the perpendicular impact of acoustic waves is then determined from the following relationship [38]:…”