Back when I was a student we played around with the concept of listening to ultrasonic echoes in a similar way. Basically human ear can get far more information

Back when I was a student we played around with the concept of listening to ultrasonic echoes in a similar way. Basically human ear can get far more information from a reflection than what one can get from it by eyes. Eventually you could do Non Destructive Evaluation better by just listening to the data and not just looking at it "Sir, this weld sounds wrong". But alas, IT pays more so that thing was buried on that lab :)