Recommended Reading
Janice Chapman's book Singing and Teaching Singing is very good. Her chapters on 'breathing' are in line with the more modern school of singing teaching, which is based on genuine science on how the body works, not myths and damaging accepted methods which seems so prevalent in singing teaching.
It is the acid test of a good singing teacher - ask them to explain 'support', and get them to back up their explanation. It is so easy to understand, but yet so few teachers really know what they are doing!
