Its probably the physics query right? It shoots out line traces to see if the physics ball is touching the ground. So how can I define an actual hit event not is touching event?
Now you can start thinking about switching sounds and scaling sounds based on the intensity of the impact. Especially useful for when you want to get those small bounce sounds (or secondary impacts).
I come from film and there you learn quickly how important sound is. I am sure you know the sound design of the first Blade Runner film. Now there is a god of sound for you The detail in there is astounding. Its also one of the tools which tells the story and can show a lot more than what is seen in front of you both consciously and subconsciously.