The primary function of the drum major during rehearsals and performances is to set the initial tempo. Then the drum major and usually the center snare drummer keep constant eye contact. The drum major follows the feet of the center snare - the center snare follows the drum major. The rest of the performing ensemble listens to the inside of the field and/or watches the drum major (except the pit). Adjustments must be made for changes of the tempo center and the distance (field placement) of the performers. Such things as cues and dynamics are for "show" only as these qualities are the result of many hours of preparation. This is a very brief and basic answer to a very complex question that is the basis for field performance and the resulting adjudicated aspects.