Time Reversal Acoustics – the Fountain of Youth? 

Brian E. Anderson

Visiting Assistant Professor
Acoustics Research Group
Department of Physics & Astronomy
Brigham Young University

Time Reversal (TR) is a method, applicable to classical wave systems of physics, used to locate and reconstruct unknown wave sources or to locate and image target scatterers.  TR relies on the principle of spatial reciprocity, i.e. the ray paths that a wave pulse will travel from a source to a receiver will be the same ray paths that the same wave pulse will travel if the source and receiver positions are interchanged.  The only major limitation is that TR relies on the invariance of the wave equation to the transform of  to  for lossless media, thus the system (propagation medium and measurement apparatus) must not change in time.  The basics of TR and its applications will be presented.  TR applications include jet noise source characterization, speech communication privacy, earthquake source localization and characterization, ground-based nuclear explosion monitoring, non-destructive evaluation of mechanical parts, and biomedical imaging.  Oh yeah, no this method doesn’t lead to a fountain of youth, sorry.