One of the people being celebrated was one guy who got his doctorate (Not the one in the picture). He had become deaf. His research was about making stuff accessible to people who can't hear, see, or understand the language. By all accounts, his work made a quite an impression. This guy was interpreting the proceedings into sign language for his benefit -- and, I would expect, any other deaf people in the audience.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/19616008@N00">Petteri Sulonen</a> from Helsinki, Finland
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/19616008@N00/14800131/">Interpreter</a>