Absorption coefficients above 1.0 reveal the spec is not a simple percentage.

Evidence

This figure shows that this material has increasing amounts of low-frequency absorption as thickness increases, and the numbers imply “perfect” absorption above about 1 kHz. The absorption coefficients regularly exceed 1.0, indicating that the specification is not a percentage absorption. There are important messages in these data: Not stated is the important fact that the density of the fiberglass board has negligible effect on the absorption coefficient, but a large effect on the mechanical strength. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1369