I just came upon your blog about E.G. White's book and I just thought you ought to know that E.G White's theory of sinus singing was disproven by the advent of imaging by voice scientists. I had to study his book as part of my doctorate in singing. There was nothing wrong with the sensations that he described, they do create good singing, but when imaging was invented, they found that the sensation of singing in the sinuses actually occurs when the nasal port into the nose is closed and the voice rings up behind the nasal cavity, spreading sympathetic vibrations into the simuses. When the nasal port is open, the sensation in the sinuses is that of a stuffed nose like when you have a cold.
Heather Lyle
vocalyoga.com