LU, safek pikuach nefesh is also pikuach nefesh. In the case of the smoke you do not go to the house and investigate. You call the FD. Screams are another matter. Some people are simply screamers. They may be very nice people but they have a nervous problem and need to let it out. In fact, the who kill their whole families are often quiet types who never argue. Then one day they explode.
