Where to place the mineral wool in cavity for a sound absorption ceiling?

Does it matter where we place the absorption material in a suspended sound absorption ceiling?

In short: Yes

In not so short: Say we have a suspended wood wool board ceiling, and we want to utilize the acoustic ceiling for good sound absorption, then using mineral wool on the cavity is a fairly simple way to increase sound absorption.

However, the position of the mineral wool in the cavity may significantly impact the sound absorption (especially the lower frequencies).
Typically, for optimal sound absorption, placing the mineral wool right on top of the wood wool board can be the best bet.

Unfortunately, this may not be a one-size-fits-all for all situations. Especially in situations where the cavity is used to store a fairly complex network of technical equipment. In this case, placing the mineral wool on the underside of the slab may be the best compromise.
However, this can result in a reduced sound absorption, even significantly reduced at the lower frequencies if compared to placing the mineral wool right on top of the wood wool board and leaving a nice air gap cavity.

Something to think about