ON THE POSITION OF THE MOUTHPIECE ON THE LIPS and the stroke of the tongue
The way in which the mouthpiece is placed is far from being irrelevant; the quality of tone and the ability to cover the entire range of each type of instrument depend on the precise position the mouthpiece occupies on both lips.
It has long been accepted that the upper lip contributes most to the playing, since it receives the most pressure. As a general rule, both first and second horns, whatever the thickness of their lips, should place the mouthpiece in the middle of the lips, with two thirds of its diameter on the upper lip and one third on the lower lip.
When the mouthpiece is placed in this way, the lips recede towards the corners of the mouth, so as to leave an opening in the centre of the mouthpiece of about one centimetre in length, taken from both lips, and one and a half millimetres in width. This opening, which is sufficient to form the sounds of the middle register, must be more or less narrowed or widened, depending on whether one wants to go higher or lower.
When these principles are observed with regard to the mouthpiece and the lips, the tip of the tongue, thinned as much as possible at the end, must close the opening left in the centre of the lips hermetically; the tongue must then retract, folding on itself, by a spontaneous manoeuvre, as if to spit out of the mouth an object the size of a fruit seed. It is this rapid movement of the tongue which produces the sound in the instrument and is called the tongue stroke, a name which, although not of the most scrupulous accuracy, has not failed to be adopted and consecrated by usage.
Several teachers, in their methods, claim that in order to produce the sound on the instrument, one must, in making the stroke of the tongue, pronounce one of the syllables daon, ta, da, tou, dom etc. None of these syllables seem to me to be appropriate, and in my opinion the only fitting one is tu made with the tip of the tongue, excluding any verbal or musical sound. In a nutshell, to make myself better understood, that quick and muffled sound made by the grain of powder catching fire.