The Impact-Echo method and instrument were invented by Mary J. Sansalone of Cornell University.  Impact-Echo Instruments, LLC was founded in 1997 by Mary J. Sansalone and William Streett, Professor Emeritus of Engineering at Cornell University. Today, Impact-Echo Instruments is the world leader in developing and marketing nondestructive instruments for evaluating concrete and masonry structures, catering to DOT engineers, construction companies, testing companies and forensic test consultants.