They may have prevented all terrorist attacks (the article only mentions one attempt), but you also have to consider their false positive rate. It says 2-5% of passengers receive secondary screening, which can involve hours of interrogation and privacy violations. This seems unacceptable, especially if your chances of getting the secondary screening (and probably missing your flight) are much higher than 5% when you're not white!

Yes, in fact this is part of what the research was testing! Here is an official summary of the actual paper: http://www.acoustics.org/press/162nd/Oehler_4pPP6.html They either told subjects that this is the sound of a chalkboard, or said it was from a "contemporary composition." Subjects found it more painful when they had been told it was chalkboard, and they found it less painful when they thought it was music. So it seems that the idea of chalk on a a chalkboard is part of what makes it so horrible, and that's probably just learned.