Find the most receptive sub-group to engage in this regularly. Within a few months, talking at the office will not be a foreign concept.

Tasteful partitions help because they break up the visual space, while letting sounds leak through. Consider some temporary partitions that you'd envision in a high-end loft, instead of ones that look sterile. Introduce plants -- real or fake.

Though I don't have a good visual model of your workspace, In my mind many open-plan offices end up looking like cafeterias, while nicer ones remind me of a children's play area at a library. By introducing some partitions and pleasant surroundings, the aesthetics will help make people more comfortable, and potentially more interactive.

That being said, white noise wouldn't bother me at all - and I don't even mind quiet office music. I think the barriers idea wouldn't really work to block sound and it would just end up making the whole office loud with chatter, which would be a major bummer to someone like me.

I completely understand that more extroverted people might need it louder to concentrate, so it makes sense to find a way to compromise, just remember your introverted brethren.

sounds like your open office is working exactly as it is designed, be happy!

your "temporary screen walls" sound a whole like like cubicles (gasp!)

I think the open office concept offers some benefits (other than just being cheap). The #1 is that communication is effortless and transparent. No need to have a meeting to relay what Alice and Bob just decided, because everyone could actively hear. However, not everyone needs or wants to hear everything that happens in the whole company.

Perhaps as a compromise you could have a "music station" where based on some revolving mechanism, each of the employees get a chance to choose the music for the hour/day/whatever. Even if it is bad and some people hate it, as long as it isn't too loud to drown out with headphones, or have a meeting over, then it could be a good thing. Plus music is awesome!