This work focused on estimating the acoustic source gains of broadband sources in a shallow-water environment. The results show that accurate acoustic source gain estimation is possible if the sources were correctly localized. Knowledge about the environment was a fundamental enabler for the acoustic source gain estimation. When dealing with multiple sources, the source gain estimation does not perform as well, but if localization was achieved, then it is still able to give accurate results at higher signal-to-noise ratios. Future research will explore how this algorithm performs on real data set(s) and in the presence of environmental uncertainty.