"David Martel" wrote in message
k.net...
Jim,

Unlike the other posters I'm not convinced you are hearing a car door.
Start keeping a diary of time, room, wind, weather, et c. Collecting a bit
of data may localize the noise and help you locate the cause. Look for
loose stuff around the house and secure it. Make sure gates shut tight.
Look in the crawl space and attic. Is something expanding and contracting
during the day?

I'm thinking it's not a car either. From the water heater maybe? Too much
sediment in the bottom of the tank creates bubbles that burst when they get
heated. You can hear that happen.