This method detects structural flaws without extensive physical contact with the structure.

For a wide range of engineers and scientists, the sound generated by a vibrating structure represents a critically important phenomenon. These sounds can be of significance for accomplishing rapid, low-cost inspection of critical infrastructure. For example, there are approximately 600,000 highway bridges in the United States. The timely inspection of these bridges requires a significant outlay of resources from federal, state, and local governments. A system capable of detecting significant structural flaws without requiring extensive physical contact with the structure would increase the frequency of inspections, thus improving the safety of the aging bridge infrastructure.