Voice is one of Fallout GURPS advantages. See: Fallout GURPS.
You have a naturally clear, resonant and attractive voice. You get a permanent +2 bonus on all the following skills: Bard, Diplomacy, Politician, Savoir-Faire, Sex Appeal and Singing. You also get a +2 on any reaction roll made by someone who can hear your voice”— Steve Jackson Games GURPS sources
With the abandonment of GURPS, Voice was recycled, image used for the Speaker perk.