Without going deeply into the Yogi theories of sound-production in speaking and singing, we wish to say that experience has taught them that the timbre, quality and power of a voice depends not alone upon the vocal organs in the throat, but that the facial muscles, etc., have much to do with the matter.

Some men with large chests produce but a poor tone, while others with large chests produce tones of amazing strength and quality. Here is an interesting experiment worth trying: Stand before a glass and pucker up your mouth and whistle, and note the shape of your mouth and the general expression of your face. Then sing or speak as you do naturally, and see the difference. Then start to whistle again for a few seconds, and then, without changing the position of your lips or face, sing a few notes and notice what a vibrant resonant, clear and beautiful tone is produced. 

Aside from the fact that "Yogi Ramacharaka" was in actuality a gentleman by the name of Willam Walker Atkinson who published a great many books on the occult and oriental philosophy, the exercise in question is one worth trying.

As Alfred A. Tomatis observed, the stapedius muscle in the ear has a connection to the face via the facial nerve, the innervation of which is reflected in the ear and voice. Of course, you can't make a face and sing. That's not the point. However, it should be noted that the experiment outlined above has a clear resonance with what Lucie Manén described as "imposto," and which Margaret Harshaw illustrated by using a curious expression (click on the labels below to learn more).

Voice teachers of Atkinson’s period talked about starting the tone from behind the bridge of the nose, which this writer understands as a sensation arising from the aforementioned innervation of facial muscles.

But enough theorizing. Go stand in front of a mirror and see what you can make of it. After all, anyone can whistle.

—Yogi Ramacharaka, Science of Breath: A Complete Manual of the Oriental Breathing Philosophy of Physical, Mental, Psychic and Spiritual Development (Yogi Publication Society, Chicago) 1904: 51.