The best free AI voice generator software available in 2024 for creating realistic voiceovers for videos and audio content is Synthesia. It offers 400 different male and female voices in 120 languages, and its built-in text-to-speech function allows for easy conversion of written text into natural-sounding speech. Additionally, Synthesia's AI voice generator is customizable to different speech styles, ages, genders, and accents, and it offers an easy translation to over 120 languages. It is also ridiculously easy to use, with the ability to turn any text into elite, natural-sounding speech with just a few clicks.