To test the hypothesis of those who deny registration, one need only apply their reasoning to a similar mechanical principle, a principle which has been worked out by engineers and is demonstrably true. A familiar example is the transmission system of the automobile.
In earlier days driving an automobile was a trifle more complicated than it is at present. Pulling power was controlled by a gearing system ordinarily made up of three forward speeds and reverse. Gear positions had to be operated manually, and before a gear could be engaged or changed the driver had to go into ‘neutral.’ Having to pass through neutral when shifting gears was not only tedious from the standpoint of physical convenience, but it interfered with the smoothness of the ride. Regardless of the driver’s skill, there was always a break in the steady pull of the motor and, consequently, in the forward movement of the vehicle every time the gears had to be shifted. In short, there were transition points at which mechanical changes were made.
Most automobiles today have an automatic transmission. All the driver need do is start the motor, put the gear shaft in the position marked ‘drive,’ release the brake, and then press down on the accelerator. With late model cars there will be absolute smoothness of movement from inertia to the highest possible speeds. But is this to deny the validity of the mechanical principle of gear ratios? Of course not. The gearing principle is still operative, but the various means developed for synchronizing them have merely eliminated the manually operated gearshift and replaced it with an automatic control devices.
To bring this analogy closer to the human voice, we can observe how this principle works with musical instruments. Examination of the interior of the piano immediately discloses that two different kinds of stringing have been used. For tones extending from the lower middle to the top the strings are made of thin steel, for the lowest two octaves, steel strings are wrapped in heavy copper wire. Thus, bass notes on the piano are not only larger, but thicker and of different metal. Regardless of this difference, the piano has a smoothly graduated tonal scale with no point of mechanical transition detectable to the ear. A major transition is made, but the gradation is engineered so as to pass unobserved.
Another analogy may be drawn by giving attention to the mechanics of the violin. Here, too, a smoothly graduated scale is the object of study. But can it be said that four separate strings of different thickness are not being used because the listener is unable to hear transitional points as the player moves from one to the other? Yet this is exactly the position of the voice teacher who denies the reality of the vocal registers. When the voice is being correctly used, and a state of perfect equilibrium attained, the singer can negotiate the transitional areas so that neither the listener, nor he himself, will necessarily be aware of the underlying mechanics. From this it cannot be logically contended, however, that the vocal registers are nonexistent. It simply means that when the conditions are right the interplay between them is not always easy to hear, at least not for the unpracticed or biased ear. The teacher who ignores the mechanics of registration is misrepresenting his professional qualifications. He is not training the voice, he is tampering with it.
Reid, Cornelius L. The free voice: a guide to natural singing. Joseph Patelson Music House, 1978.