There is a man call leak detective, who hunts for leaks in the UK. one tool he has is shutting off the water and filling the pipes with gas and using either sound or gas detector to pin down leaks.
Up until the 90’s airline in flight entertainment use stethoscope style earphones. My dad used to steal them for his workshop as a way to hear for leaks in various parts.
Our ears and eyes are very high bandwidth sensors.
There is a man call leak detective, who hunts for leaks in the UK. one tool he has is shutting off the water and filling the pipes with gas and using either sound or gas detector to pin down leaks.
A lot of the time he just listens though.