This is a common vocalise found in daily exercise books such as those by Concone or Lamperti. Since most florid passages do happen within a single key, it is necessary to be able to sing comfortably beginning on any note within that key.
These are strength exercises as well. Try to avoid increasing your volume as you ascend because that will tire you out. Instead, really pay attention to registration and move carefully through your register shifts.
This is a good key for tenors and sopranos. Mezzos, altos, baritones, and basses should transpose downward to comfortable levels. Mezzos and baritones can try A major, and altos and basses can try F, F#, or G major.
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