"The Power of the Russian Oktavist"

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Wikipedia:

Basso profondo (Italian: "deep bass"), sometimes basso profundo or contrabass, is the bass voicesubtype with the lowest vocal range.

While The New Grove Dictionary of Opera defines a typical bass as having a range that is limited to the second E below middle C (E2), operatic basso profondos can be called on to sing low C (C2), such as in the role of Baron Ochs in Der Rosenkavalier. Often choral composers make use of lower notes, such as G1 or even F1, in such rare cases the choir relies on exceptionally deep-ranged basso profondos also termed Oktavist or Octavist. Singers of the latter voice range sing a full octave underneath the bass part.