Even when sounds originate in the same room, they are often obstructed by objects like furniture before they reach a person's ears. However, because the sound remains in the same room as the listener, the reverberation effect on these sounds will not be muffled - reverberation will spread round a whole room regardless of individual obstructions.
Any man-made objects, except objects that define out-of-bounds, or a construction that is ruled to be a part of the course.
Any restriction or foreign object that reduces or modifies the cross section of the pipe to the extent that gas flow is affected or in-line inspection pigs can become stuck (ovality, collapse, dents, undersized valves, wrinkles, bends, weld drop through). Also any foreign object in the pipeline. (See pipe collapse)