During operations, always be mindful of your voice volume, as the enemy can hear you, and your choice could impact the success or failure of the mission.
Generally, use a normal voice when you have radios and the situation is calm. Switch to yelling when urgent communication is needed, like when throwing a grenade, overcoming loud external noise, or if radios aren't available. Use whispering to keep your position concealed when infiltrating behind enemy lines, setting up and coordinating ambushes or simply when you don't want the guy on the other side of the wall hear you approach him as you coordinate with your team.
