Non destructive testing (NDT) is a noninvasive technique used for characterization and inspection of the integrity of objects. NDT is an important tool for research, manufacturing monitoring and in-service inspections. Ultrasonic testing is the most used NDT technique, which for advanced composites can identify several types of defects, like delamination and interlaminar cracks. Diffuse ultrasonics has shown to be able to extract information at the microscale of metals and therefore it is believed it can be used for advanced composites to extract microstructural information, i.e. at the level of fibers. In this thesis, diffuse ultrasonic methods, together with spatial variance analysis, have been used to quantify the scattering within unidirectional advanced composites that have been loaded to different states of fiber damage. Results show that the spread in data is too large to give a clear trend of how the scattering changes with fiber damage. Further research has to be done in order to lower the spread in the results and increase the reproducibility. This can be done with higher precision in the experimental set-ups and new parametric analysis.