Air bubbles - finding leaks with a stethoscope

[cygnusecks]

You can also use a stethoscope (like doctors use). Finally, to really look like a pro, you can use one of those fetal baby monitors like I did :-) My wife looked at me with a really curious look when I had the backyard dug up trying to figure out which pipe had running water by using our fetal monitor but it worked great.