The mage can amplify or turn down the volume of sound in an area, such as making the music coming out of a pair of headphones loud enough for dozens of people to hear clearly.
Each success doubles the sound’s volume or diminishes it by half. The effect covers any sound source emanating from within a targeted spot of one-yard radius. For example, if cast upon a podium, anyone standing within that one-yard spot speaks louder than he would when standing outside it.
Silver Ladder Rote: Thunderous Whispers
It takes more than a voice that carries to make a great speaker, but this sort of thing almost never hurts, either.