Residents said that the boom shook doors and furniture, as well as startling pets.
"The only difference is, in 'Star Wars,' they get away," she said.
Boom Technology received a $10 million investment from Japan Airlines to develop a supersonic jet for commercial travel.
The latests noises were heard in Colorado.
Whatever it was has everyone from geologists to NASA baffled.
NASA says its mini-model tests have been successful.
Branson's supersonic passenger plane Boom promises 3.5 hour flights between London and New York.