A beautiful day, but very windy. Later in the afternoon after the plumbers had gone for the day, Al decided to continue his installation of a passive radon system. The PVC vent pipe is sealed into the gravel layer under the basement slab and runs from the basement into the attic, where it vents through the roof. The theory relies on the thermal stack effect, which causes a house to act as a vacuum on the soil due to temperature differences inside and outside the home. We noticed a good outward flow of air coming from the radon pipe - no restrictions in the system. As Al extended the pipe through the closet toward the attic, I heard music. It sounded exactly like a native American flute, resonating on three or four tones. I heard a G, F, A and perhaps an E. We suddenly realized that the music was being created by the wind blowing across the radon pipe coming out of the closet floor! Our house plays music! Unfortunately, after the pipe was extended, the music was silenced.