….the test of vocal ease and lasting results is to sing some high declamatory stuff, and immediately afterwards drop into a quiet mezza-voce phrase. If your piano phrases show roughness and hoarseness in the vocal quality, something is wrong. You are tightening and forcing your high declamatory work, and must attack…with more mental relaxation.
Wood, Sir Henry Joseph. The gentle art of singing. Oxford University Press, Humphrey Milford, 1930.