I guess most of us have experienced a still day, miles from anywhere and noticed how well sound has carried across a valley. Perhaps if you're chipping a motif into a stone and it makes a pleasing sound you'd go and get your mates "oi check this out, it's one of them ringing stones" sort of thing. Like you say "chicken and egg"
The way to check if a flint nodule has any flaws or cracks in it is to tap it. If it rings then it's generally ok.