Secret office sound panels disguised as abstract art

The 1970s rang. They want their sound-panels back.

The use of sound-panels was quite common in the 1970s. (http://www.audioimprov.com/AudioImprov/Speakers/Entries/2012...)

They weren't as obtrusive as most of the large speaker systems (https://i.imgur.com/9tVVsY1.jpeg) of the day

On the other hand, they weren't as good, either. Which is very likely why they more or less disappeared from use.