Although the embouchure, which means "lip set" for playing wind instruments, is recognized as the most important element for good performance, very little about parameters of it controlled by the player have been cleared and, especially at the field of pedagogy for brass instrument performance, this theme still is in chaos consequently. Considering the essentiality to know the face what occurs in the perioral area of the player during performance, mouthpiece forces and the pressures the teeth receive on its buccal surface from facial muscles were measured. Results of some experiments revealed these evident differences between very advanced and just beginning French horn players; 1) at almost all registers beginners' mouthpiece forces were greater than the advanced. 2) at extreme low register beginner's buccinator and the part of modiolus loosen while the advanced kept its tension.