Do you want music? White noise? Pink noise? (Yes, there are different colors of noise.) What level of noise works for your company culture or for the people using your office?
At my coworking space, the extroverts prefer music and the introverts prefer white noise. If you’ve got a bunch of engineers wearing headphones you don’t need to do anything. But if you’ve got a mix of people then you need to figure out what works best for your space to minimize distraction and boost productivity. When I built out my coworking space, I designed different ceiling heights to give me flexibility in setting different noise levels.
I also bought a bunch of Moshi Moshi handsets. They are fun, a great conversation point, and most importantly really help tone down how loud people talk on their phones. Often people don’t realize just how loud they’re being. If they plug in a handset suddenly they’re using their inside voices.