A long tradition of research shows that multiple acoustic descriptors are necessary to secure good room acoustics. Despite this knowledge, calculations according to the Sabine formula and measurements of reverberation time (RT) according to ISO 3382-2 alone are still used to evaluate rooms. In most rooms, we normally have absorption material on one surface only and the decay therefore will not follow a straight line according to the theory – and calculations will not always reflect reality. When testing acoustic absorbers according to ISO 354 the labs also play an important role. Differences and deviations are found, and the absorption coefficients can be seen as a specific lab product property – not as product property. This creates challenges for calculation and simulation models. Ecophon products are put into context in this meeting, and product performance and properties are discussed.