Extending the spatial extent of steady state broadband noise signals using time reversal

Exciting structures with broadband noise can be used to assess structural health by how it responds to the noise. Here time reversal (TR) is used to focus high-amplitude acoustic energy with the goal to use it to excite a structure. Equalization methods help achieve a desired spectral shape at the location of the TR focus. It is desired to increase the spatial extent of the focusing to excite larger regions. This study explores methods to expand the spatial extent first through the superposition of focusing to multiple locations and second by using a spatial inverse filter. These methods widen the spatial extent of the focusing but can come at the cost of the desired spectrum and/or overall level. The overall goal is to see if TR excitation yields higher amplitude equalized noise than the standard broadcast of it.