Classifing audio signals to detect fault
You might want to look at:

Detection of Abrupt Changes:
Theory and Application1
Michele Basseville `
IRISA/CNRS
Rennes, France
Igor V. Nikiforov
Institute of Control Sciences
Moscow, Russia

with the free pdf at:

ftp://ftp.irisa.fr/local/as/mb/k11.pdf

It's a little old, but was advanced when it came out.

There are a lot of Google results for this topic.