ElevenLabs’ computer voices are so convincing they could fool your mother. That’s both a blessing—its 30 Under 30 alumni founders are now both billionaires—and a curse for the four-year-old company. Dubbed films in Poland are horrible. A lone lektor delivers all the dialogue in an enervated Slavic monotone. There is no cast. No variation between speakers. Young audiences hate it. “Ask any Polish person and they will tell you it’s terrible,” says Mateusz (Mati) Staniszewski, the cofounder of AI s...