I would here remark that some musicians, (particularly those who are not teachers of singing) as well as a few physicians, (who cultivate the voice according to their own invented and improved theories, set forth with a grand display of scientific knowledge) object to the term registers, as applied to the changes in quality of the human voice; arguing that the tones are all produced upon one and the same small organ, the vocal cords, and must, therefore, be all alike; a few, however, reluctantly allow that there is a sort of natural change in two or three places in the voice, and call it “a hitch,” or ”a break,” or “a something they do not comprehend,” etc.; now Nature has made certain fixed, regular differences in the quality of the tones, — as one may hear, who listens to an ascending scale, sung slowly, or may feel, as well as hear, in his own voice, should he sing it himself, — and to unite, to harmonize these differences, to produce one unbroken whole, is the object of the voice trainer; that this may be done successfully, these changes in quality must not be ignored, but their position and characteristics must be determined, defined and understood; the word “registers” seems to me to be as proper and significant for this purpose, as any other, especially since these strenuous objectors, like the greater number of reformers, are content to take away the old, without offering anything either new or better in its stead. What matters it by what name we call them (unless we could hit upon exactly the right one that would please everybody) so long as they are perfectly comprehended? Again, the term registers has been used in this connection for so many years, that it is now better understood by musical people, than even a more appropriate one would be; therefore I shall employ it throughout these talks, in speaking of this change in the quality of tones.

Barnette, Annie MR. Talks about Singing; Or, How to Practice. Chicago Music Company, 1886.