Sorry yo hear of your illness Kai Wee. I trust you will be back on you feet in no time.
I share your fondness for "singers" Rahman. I wonder if it has more to do with just tempering the blade. I would have thought that many of my older blades that don't sing would also have been tempered. I have thought that the pleasant ringing might have more to do with the types of metals used in the forging. Perhaps someone knows more.