This is the name given to the towers that are set up at large live events, for the purpose of diffusing the sound over extended distances away from the stage. P.A systems are set up on the towers (in addition to the P.A's present onstage) which consent a virtually uniform sound over very wide surface areas.
When several sound sources are combined, each of which generates a certain amount of dBspl, it isn't possible to simply sum up these values, but we should rather use the following empirical formula
