Want to raise the intensity of a moment? This is when you take an already angry voice and turn up the volume to pump it all the way up to mad. This voice let's you know that things just moved to another level of real.
When your story is reaching a climax or turning point, you might want to employ the mad voice to up the stakes and levels of intensity. A mad voice symbolises breaking point or the moment of no return. It could be emloyed by the antagonist just before the final act or assault; or the protagonist to declare "We are not going to take this any more!" The mad voice typically denotes a change to the tone of what is happening and points to some kind of confrontation that is to come.
When the audience experiences the mad voice they know that the character means business. It is a voice which really draws them in and increases their investment in the story. Make or break, the mad voice will lead you to the point where we see who is victorious and who will fail.
Two things signify the mad voice. One of those is volume. The louder the voice the more madness is conveyed. There may be a roughness or breakingness to it to show that this character is losing control or has had enough. But the second way deals with the words being used. Cuss words and strong perhaps violent words and descriptions help signify madness of voice.