Correct postural balance is the basis for good breathing and voice use.
Alexander Technique is nowadays part of the standard curriculum in most of the leading drama and music colleges of the world. Lessons can help voice users develop greater stability (less fear of losing their voices), and full power, range and facility.
Professional singers and speakers are regularly sent to Alexander teachers to assist with eradicating such things as nodules, or correcting breathing problems.
The Technique differs from most disciplines by asking what the voice user might be doing, at an unconscious habitual level, which might be interfering with the innate efficiency of their vocal and breathing mechanisms. It offers a methodical way of eradicating that interference, thus allowing the innate voice to work. This approach leads to the freeing of the individual characteristics and qualities of the users voice.