You searched for: “acoustical clouds
acoustical cloud (s) (noun), acoustical clouds (pl)
A panel or similar device that is suspended from an auditorium ceiling: An acoustical cloud was positioned above the orchestra so it could reflect the musical sounds better for the audience.

One music hall had several acoustical clouds suspended from the ceiling, however the architect forgot to take into consideration that heat from the audience and the performers could send the acoustical clouds spinning around over the heads of the audience and therefore the architect had to come up with a better solution.