I completely agree, however, one of the neighbors stated they were "getting ready for work" when they heard the hollering.. That could mean they are inside the house getting ready or they are outside the house getting ready. I assume they did hear arguing, but it may have not come from the Sievers house. It may have been one of the neighbors, who did not hera anything, because they were arguing themselves..
Also, the neighbor who heard the "shrill" is right behind - or east of- the Sievers' house. If she did hear the shrill and nobody else heard it, it could mean that that was the direction of where the sound was traveling to, or the neighbors did not hear it for any other reason.
-Nin