How do I produce vibrato?

What happens if you exceed a usual vibrato frequency?

• A vibrato frequency is usually somewhere between 0.50 Hertz to 3 Hertz. However, if the human voice were capable to produce a vibrato frequency that goes into the human-hearing range (20 Hz to 20000 Hz) then would we hear an additional pitch in addition to the note we are adding the vibrato to?

• Answer:

  Vibrato is modulating the pitch of a note, so that the original note goes up and down.  The frequency of the vibrato is the speed of the cycle of up and down around that note.  Even if the vibrato frequency went up to 20,000Hz the pitch of the original note would never extend beyond the original vibrato range, it would just "vibrate" faster.   Eventually I think the ear would be unable to distinguish the pitch changes and you would just get a slight buzzing effect.