Linda, coincidentally we had a family here in Arkansas that the wife was a nurse of some sort and the father in the restaurant business that did the same thing. Only they were running a generator to get electricity to their house. Do you think it may be a generator you are hearing? It is also very loud. I do not know why the people in Arkansas did it because the gas to run the thing would be expensive unless they had outstanding bills with the electric company and that was the only way to get electricity to the house. As for the missing girl, I don't blame you for your concern. It is plausible that they could be hiding her and using the generator to keep her alive. Do you have meter readers that come out to the houses to read the gas meter, electric meter, etc.? If so, try to catch him or her when they read your meter and ask questions about the neighbors house because chances are the meter reader will think them odd as well. You might ask him if they have electric on, what he thinks is running over there all of the time, etc. This will help you in making a decision as to whether your idea is plausible. Just some suggestions. Let us know how things progress. Rhett.