Absorption where there is no wall left
Suspended acoustic baffles that hang from the ceiling, including the SCH! Hatch and Shade designs. In a modern office the ceiling is often the only surface left that is not glass, whiteboard or window.
Why overhead works
Sound rises and reflects off a hard ceiling back down into the room. Treating the ceiling puts absorption directly in that path, which is why baffles often do more per panel than the same area on a wall.
They also sit above head height, so they take no usable space and nobody leans on them.
Installation is the thing to check
Baffles hang, which means fixing to the ceiling structure or an existing grid. In a leased building that may need landlord consent, and in a room with a suspended ceiling it needs the grid to take the load.
If fixing overhead is not possible, hanging acoustics and wall tiles are the alternatives.
Part of a wider treatment
Ceiling baffles alone will not fix a loud room. Spread absorption across surfaces: see acoustic solutions for the full picture and the SCH! collection to keep the look consistent.