Pitch

• Vibrato can come from a variation in pitch or in volume. Generally, the variation in pitch will go both above and below the main pitch, although some may choose to focus on one direction or the other. To practice a pitch variation, simply play a mid-pitch note and hold it. Try to make the pitch waver using only your trunk muscles and lungs. Avoid using the upper throat and lip, as changing these can alter your tone. Try to experiment with changes in air pressure, which should originate low in the stomach and lung area and flow through the larynx. Think of trying to fog a mirror with warm, thick air, and then changing to cool air. In time, you will discover exactly which muscles will produce these changes.
  
  

Volume

• Volume usually also varies when producing vibrato. Sometimes it is the only variation used by those who are not able to master the pitch variation, a practice which can be perfectly acceptable for amateurs. To practice volume, try setting a metronome to about 60 beats per minute. Play a sustained note at a hushed volume, or a mezzo piano. At each beat, pulse to fortissimo. As you become more skillful with volume control, perform this exercise with different volumes, such as from mezzo piano to mezzo forte. Your ultimate volume variations will have to be noticeable, but not as obnoxious as a jump from pianissimo to fortissimo. As you gain more control over your trunk muscles, you will learn to control the volume more subtly.
  
  

Speed

• Set the metronome to 60 once again. Use the same exercises as above, but try to shorten the amount of time between variations. You can work on either volume or pitch, or a combination if you have begun to master both. The target speed for your vibrato depends on personal taste, but on average, aim for about 4-5 variations per beat, so that you are producing about 200-300 variations per minute. Although initial exercises typically use a metronome to establish a vibrato, the vibrato should not be regularly measured once you establish it. It is easiest to begin with this measured beat for practice, but this should fall away as you become more skillful with your vibrato.