I disagree with the above essay, where saying, that Feodor Chaliapine's was a "bass" voice....
He sung bass roles in operas. However, he performed bass and baritone and even into tenor, as moved him or necessary. He was able to produce such a full range of the scales or across tessatoras, with ease, with complete mastery, because of Learning and that adherence, to what was learned.
Why do you think non other than the greatest orchestra master, Arturo Toscanini, said; "(he) was the greatest opera singer he had ever conducted music for."?
The great opera singers and Chaliapine may have been the greatest have qualified, one on one, teachers, to begin with.
Wherewith and whereby they learn, as follows: They learn voice placement resonance breath control singing on the breath and then to sing- to toss off song or the aria with sublime ease -to give the appearance that it is the easiest thing you're happy to show to your audience and they are just as pleased to see and to hear, above all, in turn....