How do Oktavists sing so low?
It is similar in nature to subharmonics. Apparently there is a technique where you "swallow your larynx" and depress is a very large amount using muscles almost never used for singing. Then, once it is extremely depressed, you can sing notes 2-3 steps lower than your usual low.
What is an Octavist?
An oktavist is an exceptionally deep-ranged basso profondo, especially typical of Russian Orthodox choral music. ... Russian composers often make no distinction between a basso profondo and an oktavist, or a contrabass singer.
What is the vocal range of a basso profundo?
In vocal music, the bass is the lowest male voice, with a typical range from the second E below middle C to F♯ above; the basso profundo is low and rich, while the basso cantante (“singing bass”) is lighter and more lyric.