In light of all this controversy on the throat, throat attacks etc, I find it necessary to post a few of my thoughts here for your "enightenment"
On The Glottis
The glottis is the part of the voice box that consists of the vocal cords which are two fibrous sheets of tissue in the larynx,and the v-shaped slitlike opening between them [less than 1inch long]. It is the glottis through which air is breathed and it is the glottis which has a MOST important role in regulating the air stream as it is our FIRST point of resistance in the throat!!
This resistance in exhilation is what gives steadiness & control to the hissing sound we use in controlling our air stream being emmited. This blowing and holding back this strong column of air has to be resisted somewhere.A strong muscle [the diaphragm]does not have the acute ability to vary the volume from a very soft pianissimo to a forte with a steady degree of control.Now this blowing and holding which I call "the grunt" in my book is nothing but a case of ISOMETRICISING your air and THIS is where the role of the glottis comes in. It is the glottis that regulates the respiration by exerting an obstructive influence on the air stream, NOT the diaphragm as many brass teachers profess!!! In obstructing your air column by means of the glottis is how this "grunt" is produced. The more pronounced the "grunt"is the smaller is the opening in the glottis.This would be used for softer playing especially attaining more control of the air stream. Conversely for loud playing we would have a larger opening in the glottis. SO, the glottis can be considered as an aperture used to provide us with more resistance which in turn helps the diaphragm and all of its related muscles as it contracts when we exhale........
For brass players, the size of the opening in the glottis will vary with the dynamic levels of the music.A SMALL opening for the soft and a large[wide] opening for the loud. I say that the correct use of the glottis is quite natural and most effective in developing and acquiring a STEADY degree of control of the air column........... IMPORTANT POINT !!!
My concern here is for the player playing with a closed throat !!! If the player lacks the ability to control his breath he will most likely constrict the glottis by forcing his breathing. Therefore there will be a marked narrowing of the glottis during this forced exhalation so that the glottis will tend to narrow during the playing of loud tones creating THE CLOSED THROAT !!!!
The better players will open up to produce louder, bigger sounds where others will open very little. THIS IS WHY THE BETTER PLAYERS HAVE MORE SUCCESS THAN THE OTHERS IN OVERCOMING THIS TENDENCY OF THE GLOTTIS TO NARROW WHEN THE BLOWING OF MORE INTENSE SOUNDS ARE PRODUCED THROUGH FORCED BREATHING. This shows us that the glottis is both a voluntary and involuntary control mechanism. We must always have conscious control of the glottis when playing. I believe that this can be a very effective tool to address one of the "problems" of the QUALITY of sound and control of the air stream which points DIRECTLY at the source.
By developing your ability to blow your horn with the ease and freedom [that an open glottis will give you], you will see how much more RESONANT and full your instrument will sound.
Remember: the glottis is voluntary and involuntary...so it is up to the player to overcome the tendancy of the glottis to constrict and become narrow when one is blowing louder and higher!!!
IT IS A PROCESS WHICH REQUIRES CONSTANT ATTENTION WHEN WE ARE PLAYING OUR HORNS... IT MIGHT EVEN TAKE YEARS TO FULLY DEVELOP THIS NECESSARY CONTROL.