In this paper the acoustic properties of porous granular materials made from rubber re-cyclates have been examined. Comparisons are made between unconsolidated rubber crumb and crumb consolidated with an adhesive for different sized grains and material thickness. The overall absorption by applying adhesive is increased in larger grains, although absorption is observed to increase in materials made of smaller grain sizes. It is shown that the relationship between the two states can be partly described by the change in flow resistivity and first resonant frequency.