Toning

Sitting or standing erect so the abdominal area is free to move, inhale slowly and deeply through the nose, releasing the air through the mouth while sustaining a single vowel on a single tone. Repeat with a different pitch. Repeat again, this time with a syllable such as Om, lam, hu etc. Explore different combinations of vowels, syllables and pitches and sense the location in your body affected by the vibrations.

Sounds of Healing.  Mitchell Gaynor, MD. Broadway Books. 1999.