I have read through a bunch of patents, but admittedly skimmed through many of them not being able to follow them really But cannot recall seeing any mention of rounded corners. You don't happen to know which patents?Leob.
There are patents describing the use of rounding the corners and why.
But I must admit I have never really heard much difference in sound?
I do round my small card panels though as this stops the corners flapping around uncontrollably.