Abstract
It is well known that sound absorption and sound transmission properties
of open porous materials are highly dependent on their airflow resistance
values. Low values of airflow resistance indicate little resistance for
air streaming through the porous material and high values are a sign that
most of the pores inside the material are closed. The laboratory
procedures for measuring airflow resistance have been stan- dardized by
several organizations, including ISO and ASTM for both alternate flow and
continuous flow. However, practical implementation of these standardized
methods could be both complex and expensive. In this work, two indirect
alternative measurement procedures were compared against the alternate
flow standardized technique. The techniques were tested using three
families of eco-friendly sound absorbent materials: recycled polyurethane
foams, coconut natural fibres, and recycled polyester fibres. It is found
that the values of airflow resistance measured using both alternative
methods are very similar. There is also a good correlation between the
values obtained through alternative and standardized methods.
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