When discussing those female singers whose voices sit below the accepted range of the contralto, I believe that we should move away from the terms female tenor and female bass. Instead, we should move towards terminology that is more descriptive of the timbre of the voice, and of the method of vocal production engaged to attain the required pitch.
It is for this reason that I suggest the terms contralto profondo for female tenor and oktavistka for the female bass.
I would like to demonstrate why I believe these terms are more appropriate.
In the case of the female tenor, women who sing in the tenor range are using the lowest register, the chest register, for the majority of the notes they produce. They may move into the middle register for the highest notes above F4, but they may also extend the use of the chest register to cover these notes, particularly when required to sing fortissimo. The chest register in any singer is darker and thicker than the other two registers. By contrast, a male tenor is spending the majority of his time in the middle and head registers. The head register of the male tenor is tight and piercing, not cavernous and expansive. Thus, in the case of the female tenor, both the method of producing the notes, and the timbre of the notes themselves, have little in common with the male tenor. In fact, she has more in common with the registration changes of the basso profondo, making the term contralto profondo, rather than female tenor, a more appropriate description of the voice type.
The same case can be made for the female bass. We use the term oktavist to describe a male singer who can sing in the octave below the basso profondo. Thus, rather than the term female bass, I suggest the term oktavistka. This term, oktavistka, is not in the Russian dictionary. An academic, who specialises in the Russian language, and who is a colleague of mine, has advised that the suffix –ka feminises the word oktavist. Hence I have used this neologism…
To adopt the terms contralto profondo and oktavistka would, I believe, give a greater credibility to the voice types, with respect to both the singers themselves and to their potential audience. “Low ladies” would no longer be seen as “women who sing like men”, but would instead be seen as “women who sing low”.
Now that I have explained these terms, I would now like to integrate them into the existing contralto terminology.
The three existing contralto voice types are (with the exclusion of the coloratura contralto) the lyric contralto (the highest contralto Fach) the dramatic contralto (the lowest contralto Fach in mainstream opera) and the tiefer alt (the current lowest contralto Fach, which I would consider to be the “Alto 2” of an eight part chorus, and which is seen rarely in opera; the role of Gaea in Strauss’ Daphne being the main example). The contralto profondo would sit below the tiefer alt, and the oktavistka below the contralto profondo.
With respect to range, timbre, resonance and vibrato, I would expect a tiefer alt to be comfortable down to Eb3, have a solid D3, and have a possible C3, though it may be raspy and not what one would consider a "soloists" note.
The contralto profondo would, I believe, be able to sing down to B2/Bb2, with a full resonant sound of operatic quality, with a full, vibrant vibrato and no vocal wobble. The sound would be richer and darker than the usual contralto sound, with similar qualities to that of the male baritone with respect to vocal colour. Here are two examples of singers that I believe demonstrate the qualities of the contralto profondo Fach.
"Una furtiva Lagrima"
Songs of Araby
"Gloria Patri" from Dixit Dominus
If the singer was able to sing in the range A2-E2 and below with a full and resonant sound, and with full vibrato, then I would consider her to be an oktavistka. To the left is an example of a singer that I believe demonstrates the qualities of the oktavistka Fach.
If a female singer were to sing C3/Bb2 with full resonance and a full vibrato, but produced a thin, pushed down quality at A2-E2, then I would consider her to be a contralto profondo, and not an oktavistka.
In each of these voice types, it is important that the sound produced is full, resonant and executed with a full vibrato.