This is a pretty interesting paper. I was not aware of the acoustic properties of silk (a fabric that continues to surprise me). The ability to actively dampen noise emission would obviously be of interest to ninja assassins but as someone who has hearing challenges I think exploiting its properties to make it into a full garment microphone might be an interesting application. Based on the sound levels in the paper I don't think it would work as a speaker however which is kind of good because everyone having their own mood music all the time would be super distracting.