If you type on linear MX switches, as people have said, they'll be virtually silent. But don't try MX reds for this. The heavier the spring, the quieter it will most likely be. That's becasue 1.), if you're not using O-rings you'll be less likely to bottom out on heavier springs, and 2.) even if you do bottom out using o rings you'll still be hitting the bottom with a higher force, and thus making a louder noise.
Quietest would be MX superblacks with orings and landing pads.