Such a horrible and politically incorrect word, the word ignorance !
This is about correctness and not about politics. It’s the subject of anatomy.
Most vocal coaches I have had know little to nothing about anatomy. Some have misunderstanding and misinformation that they pass on to their trusting clients, who sadly do not know any better.
As if that were not bad enough, what they spoke about was either invented or was revealing of their ignorance (that bad word, again).
Ignorance can mean to have ignored facts or to simply have not studied the facts. When it is applied ignorance, fantasy may enter and confabulation or simply lying, to hide the ignorance.
Specifically, there are things which should be known but were either never taught or were never studied by some vocal coaches. Is it negligence that things were never studied or learned, or was it purposely done? Either way, the result is the same. Singers are taught things that are not only incorrect, but are also potentially harmful.
Fortunately, there have been some very well and broadly educated pedagogues in the field of voice instruction.
The worst thing about ignorance of anatomy is that it can be dangerous and result in injuries to the vocal apparatus or can cause other deleterious effects.
Breathing And The Breath Apparatus
A vocal coach may tell you to “fill up down here”, as the coach pats the lower abdomen. This means to put the air into your lower abdomen.
Your lungs do not extend that far down into your body. If you have air in your abdomen, according to the Yale University anatomy class I have done, you must immediately go into surgery to save your life. That is reality. Air does not go into your abdomen from breathing in. The exception would be from injury to the lungs or intestines.
When coaches pat their lower abdomens, they also may push out on the muscles and are doing nothing more or les than potentially causing a pot belly on their bodies.
Cause and effect exist universally, but the cause of the abdomen protruding is the contraction of the diaphragm, which moves downward and causes a partial vacuum in the lungs and air is drawn in.
As the diaphragm descends, it puts pressure on all the organs beneath it and they bulge, having no room to move downward, being enclosed by the pelvic bone and the pelvic floor. Thing of a donut being smashed (cause) between two books and the circumference of it expands, as a result (effect).
Breathing Is Natural, But…
When you are born, one of the first things you do, and without thinking, is you breathe. It is natural. It is automatic. It is done without thought. Breathing is mostly involuntary, until the singer takes over the control of it.
When you change things from what is natural, it gets more difficult, but there must be control of the breath for the purposes of turning your body into a musical instrument, being a singer.
If you force your abdomen outward, you don’t gain any space for more air. At the same time, if you force it to remain flat, you cannot get a full breath because the diaphragm will be inhibited from descending upon its contraction.
Your lungs are in your chest. If you use the intercostal muscles, the ones between your ribs, to hold your chest in place and to not let it naturally expand, as the lungs inflate, you cannot and will not get a full breath, if and when you need one.
Under-breathing and over-breathing are not natural and can be problematic for singing. The solution is simple. Take in enough air to do the phrase. A slight amount more is comfortable, but a slight amount less is not comfortable, and you can even feel oxygen-starved from under-breathing.
Keep it as simple as you can but be pragmatic and proactive.
Participate. Learn. Practice.