We also have a similar open gallery corridor, additionally with a large open space. A replacement workplace was also planned there. The sound carries everything upwards. I wouldn’t make the separation that will now arise fixed... what about fabric? Maybe revert to something tried and trusted and hang thick brocade fabric. I’m not saying that fits the style, nor that I like something like that - but maybe it doesn’t look so bad if you can draw it back again in the evening :)