Perfect Paul is one of the three voices that projectaba the Speech Plus CallText 5010 human speech synthesizer produced in 1988. This synthesizer had three voices: a female, called "Beautiful Betty", another child ("Kit the Kid") and a male ("Perfect Paul"). But above all, Perfect Pau is known to be the voice of Stephen Hawking.

In spite of the improvements in the software and hardware of the interface, Hawking never stopped using this voice of primitive technological aspect. The reason has to do with personality traits: changing your voice would be like changing your face. Simply, Hawking identified with his old Calltext, and moving to a different style of voice would make him feel a stranger. Although there may be other reasons; He was once asked why he did not use a voice with a British accent, more typical of an Oxford native like him. Hawking replied: "With the American accent, I have much more success with women."