Musicians

Not to be confused with minstrels.

When an army marches, it does so to the beat of drums and the call of blaring horns. These instruments are used to announce a unit's presence on the battlefield, bringing fresh hope to friends and worry to enemies. More than this, a unit's musician is crucial to keeping order when the unit attempts to change formation or should it need to rally. For trained troops, a prearranged sequence of notes can carry as much information as a bellowed order, and can do so more clearly and with greater speed.

Source
pg. 95
 * Warhammer Fantasy Battles (8th Edition)