And how well would it take to master it?
(don't say a lifetime ,by master I mean total control over it )
hi there again.
most everyone has an octave already at their disposal. Even the folks on the TV shows.
Most singing issues are based on how well one can "master" the breath support concept, plus the ease with which one lets the sound out of the vocal tract area ( from the vocal cords on up and out to the lips).
Total control? I don't think it's humanly possible. Mastery over the whole voice takes a lifetime. Being able to work adequately in the field takes at least 4 years in a conservatory or university.