Locating damage in structures is a critical part of the complete structural health monitoring (SHM) approach. Most of the structures ideal for applying SHM exist in environments subjected to ambient noise. With embedded sensors in structures, a large collection of data can be gathered for processing. One use of the time domain data is to perform cross correlations between sensors, which result in a Green’s function estimate of the structure between each sensor combination. Using these results one can perform matched-field processing and signal processing techniques to locate a weak source representing the damage. Matched-field processing correlates the isolated damage complex spectral signal to a replica field of the structure, which in most cases this is produced through simulations. This process was demonstrated through experiments on an aluminum plate and a composite wind turbine blade where the replica field was determined experimentally. The results demonstrate the feasibility of this method.