I would say that most people that own any hydraulic equipment do not know what cavitation is or what it sounds like.
A simplified answer, is that cavitation is developed when the vapor barrier of the liquid is broken and bubbles form, and when the fluid moves to a pressurized area, they will burst with high energy, and if done for a while, then it can erode metal to the point of destruction. While in the Navy, I listened to ships cavitation, and if you know anything about cavitation, in reference to ships propellers, that when something is cavitating, any rpm above that will not produce any gain, otherwise, you lose efficiency. If you look at some of the old ships propellers, you can see the effect of cavitation.