The "modern" open-plan office in which I work is particularly bad at acoustics. The dining area has a dome, which looks nice but sounds like an echoing railway station. I avoid it because I can't make out conversations in that kind of environment. Said dining area is isolated from the rest of the office by a partial wall that does not go all the way up.

All walls and ceiling surfaces are smooth and flat to maximise acoustic reflection. When we first moved in, the glass-fronted meeting rooms were echoing little boxes that were also impossible to hold conversations in, so we had to fit fabric acoustic suppressing wall hangings.

Offices could do well to learn from the "modern bar vs. traditional pub" layout approach. The bar is open and loud; conversation requires either out-louding people or leaning into someone's ear. The traditional pub "snug" has wooden half-partitions into booths, lots of fabric on the seating, maybe a few wing chairs, and a twisty internal layout. The ambient volume is much quieter.

An office laid out like a snug would still technically be "open" but would stop noise travelling across the office. Even just an acoustic suppressant ceiling would make a big difference.