"Neuroscientists from KU Leuven measure brainwaves to determine whether people understand what they hear":  https://www.eurekalert.org/pub_releases/2018-03/kl-gtm030718.php 

The new technique was developed by Professor Tom Francart and his colleagues from the Department of Neurosciences at KU Leuven, Belgium, in collaboration with the University of Maryland. It will allow for a more accurate diagnosis of patients who cannot actively participate in a speech understanding test because they're too young, for instance, or because they're in a coma. In the longer term, the method also holds potential for the development of smart hearing devices.