One of the curiosities of operatic musical nomenclature is the huge number of classifications created for the singing voice, compared to the relatively few such classifications for choral singing. A male singer of classical music, in the most extreme classification, can be said to fall within one of at least fourteen (purported) ranges. From bottom to top: basso profundo, basso cantante, basso buffo, bass-baritone, baritone, lyric baritone, dramatic tenor, Heldentenor, spinto tenor, lyric tenor, leggiero tenor, tenore di grazia, countertenor, male soprano. Women, on the other hand, are commonly classified as falling into one of five: contralto, mezzo-soprano, dramatic soprano, lyric soprano or coloratura, along with predictable sub-categories, such as "dramatic coloratua," etc. I would call the female ranges a more nearly reasonable sample of the kinds of voices one can hear in opera. The many male ranges are not informative. Most often, they reflect color of voice or flexibility of voice more than range of voice. Sometimes they overlap, or the nomenclature overlaps with that of female ranges. (It seems reasonable, for example, to call Philippe Jaroussky an alto, but one would never call Schumann Heink a tenor.) The reasons for all this are linked to aesthetics, repertoire, sociology, gender, history, theatrical convention, the science of harmonics, and, not infrequently, silliness. In fact, all voices—absent the drama of the stage, or of being Yma Sumac or Ivan Rebroff—break down reasonably to the very ordinary and unglamorous SATB scheme of choir music.
And that, in my judgment, is where the problem lies—choral singing versus that of individual singing actors. A nomenclature appropriate to anonymous individuals forming a global sound-cluster cannot be identified by so many fine distinctions. Some sub-groups within the choir sing high, some sing low, and all are capable of shifting, shading or coloring the sounds upward or downward, as required to cover the needed range of sound. In operatic singing, I would contend that range of voice is not so crucial as is commonly thought. Marilyn Horne is properly called a mezzo-soprano, by convention, but her upper register was extraordinary, and, repertoire permitting, she could equally legitimately be called a dramatic soprano, or, in some instances simply soprano, if one is to judge by singable note range. But that is not the issue. It is color of voice that matters. Darker ranges have serious or somber overtones, and thus lend themselves to certain roles and repertoire. So we enter the realm of theatrical representation. Darker versus lighter voices have sexual connotations. Voices suggest age. Higher male voices speak of youth, darker or lower voices speak of age or sometimes malevolence. ("Credo in un dio crudel!") would not be very convincing falling from the lips of Tito Schipa.)
If all this is granted, then we must consider the case of individual personalities—something that co-resonates with "star power." Some personalities, in combination with certain personality types, can be most attractive. The perfect "little girl" sound of Galli-Curci's voice, in combination with her small, almost fragile body and her refined manner, all came together to produce one of the most popular and beloved sopranos of all time. A very high male voice, coupled with an extroverted, even bombastic personality can give rise to the famous (or infamous!) tenor stars of opera. A gentle and tender tenor voice, however, in combination with an elegant, modest or somewhat withdrawn personality (Tito Schipa, Ferruccio Tagliavini, Alfredo Kraus) can produce a star who, while usually not enjoying the extreme popular success of the bombastic type, can nonetheless win a very large audience of aesthetes, who are delighted by refinement and delicacy. (The Great Couperin, in his treatise on the art of playing the harpsichord, said that he, in matters of style, would much rather be pleased than surprised!) At the lower end of the vocal spectrum, a big, booming bass voice, coupled with an extremely comic figure (Salvatore Baccaloni) can redefine bass singing in the direction of comic, or "buffo" singing. Pol Plançon, on the other hand, was the exemplar of the famous French tradition of basso cantante singing, an uncommonly elegant art. The vocal classifications applied to any of these individuals usually reflects, in some degree at least, their appropriate repertoire, in combination with their public persona and the degree of acceptance their particular kind of singing and acting has earned them. Finally, men who sing extremely and artificially high, and who portray females on stage, or females who sing low enough to be taken as a boy, characteristically inherit from the audience a kind of fascination with the trans-gendered that can be reflected in the names given their particular kind of singing—there are, for example, subtle differences of perception that arise from being called a "countertenor" as opposed to being called an alto, yet from a purely musicological point of view there would not be any difference. A good male alto, if one cannot see him, can—and often does—sound identical to a female alto.
One could go on, but the essential point is that in operatic voice classifications, one is never dealing with voice alone, and while the many vocal classifications might not survive the cold and objective eye of the musicologist, they nonetheless speak in a direct and important way to the many fans of opera who actually care about why their favorite soprano, alto, tenor, or bass is different from (and usually superior to) all the other sopranos, altos, tenors or basses offering their artistic and aesthetic wares for sale. And of course, the classifications also matter to music critics ever bent on demonstrating that they are capable of making ever so much finer distinctions in such matters than anyone else. Present company excluded, of course! That goes without saying:D