Many papers have reported both theoretical and experimental results on the absorption coefficient of double layer microperforated (MPP) absorbers. Conventionally, the equivalent electrical circuit (EC) formulation has been used to predict the performance of single and double MPP liners. However, the impedance transfer (IT) approach, recently proposed by other authors, revealed some discrepancies with the traditional EC analogy. This paper compares both formulations, affords a novel justification for these discrepancies, and provides experimental absorption curves of purposely designed double layer MPPs which match better with the IT approach.
