I looked over the patent yesterday, I think someone linked it in this thread. It would “listen” for the sounds of impending structural failure, by comparing the sounds in the hull to a dataset of previous test dives. One of the passengers on Titan’s 2nd dive said it made cracking and popping noises as it got deeper but the patent intended to detect a change in acoustics (in conjunction with stress sensors) far enough in advance for corrective action.