In this paper, we report on measurements of the acoustic absorption coefficient of ETFE membranes and cushions by two types of measurement approaches. The experimental results are compared with material simulations in ODEON® room acoustics ver.17. The absorption was determined via the assumption that the energy which passes through the foil can be considered as absorbed energy, and therefore can be measured in a transmission room facility based on an ISO 10140-2[1]. Also, the acoustic absorption was measured in a reverberant room, based on an ISO 354[2] test arrangement. Due to the high acoustic transparency of the membranes at low frequencies, the two approaches were adapted with the aim of minimizing measurement artifacts. The different results were compared and interpreted in view of getting insight into the physics of the absorption mechanisms and the reliability of the used measurement approaches.