Acoustic Foam: is it all the same?

Just a quick one. A common criticism of acoustic foam is that it will not absorb low frequencies. This is a very common point of view expressed on forums that is simply not true. At risk of repeating myself, the ability of acoustic foam to absorb low frequencies is related to thickness, structure and density. Thickness is the most critical variable. A 150mm section acoustic foam panel such as the SA600-150 absorbs 100% at 160Hz and 60% at 100%.(Independently tested at RMIT acoustic lab) Placed across a corner greatly improves the effectiveness of this panel, which gave rise to the design of the BT600-150.
It’s probably worth mentioning that any thin acoustic treatment will not absorb low frequencies – egg cartons, carpet, eggshell foam, curtains etc.