Yes, I don't understand this acoustic monitoring concept... I'm curious what the logic behind it was. It just doesn't seem like there would be enough time to take action once the monitor starts to detect failure.
James Cameron said it looks like they had dropped their emergency ascent ballast before the implosion, so they may have gotten enough warning to take action. But I would guess that system was never tested to failure in real life.
It will be interesting to see which of the novel innovations supposedly enabling this unconventional design failed, if it can be determined. Rush also lampshaded the fact that his company had "successfully" bonded the titanium endcaps to carbon fiber despite that being contradictory to conventional materials science wisdom, reading the patent for the monitoring system it looks like it may have been intended to provide warning about those bonds failing too.
Carbon fiber, however, is not known to gradually fail.