 Pitches are changed in part through altering the amount of muscular contraction in the lip formation.The performer's use of the air, tightening of cheek and jaw muscles, as well as tongue manipulation can affect how the embouchure works.Maintaining an effective embouchure is an essential skill for any brass instrumentalist, but its personal and particular characteristics mean that different pedagogues and researchers have advocated differing, even contradictory, advice on what proper embouchure is and how it should be taught.