Yeah.... pretty much. Or when you come into sight. It's why I switched to muscovies. We were being held hostage in our house because the silly things would quack like crazy when they saw us walking around in the kitchen and dining room (even though they were set almost half an acre back.) Obviously our neighbors did not like that. So we had to stoop when we walked around and not turn on any lights in the house. During the day when they would free-range, they'd also come to our patio sliding doors and just stare inside to look for us. If they saw us they would set up the unholy quacking again.
They're very endearing and I loved them and if I didn't have neighbors, I wouldn't have minded the noise.