It doesn't matter if the voice is a perfect facsimile — it only matters whether a court can be persuaded that the result is derivative.

As the article notes, the AI doesn't even have to be trained on Greene's voice for him to have a case.

> Grimmelmann said Greene doesn’t necessarily have to show definitively that Google trained NotebookLM on his voice to have a case, or even that the voice is 100 percent identical to his. He cited a 1988 case in which the singer and actress Bette Midler successfully sued Ford Motor Company over a commercial that used a voice actor to mimic her distinctive mezzo-soprano. But Greene would then have to show that enough listeners assume it’s Greene’s voice for it to affect either his reputation or his own opportunities to capitalize on it.

In other words, can you guess who someone is impersonating even if their impersonation isn't a perfect simulation?

There's a lot of characteristics to people's voices. Tons of people impersonate Trump purely through cadence. Same with Obama. How many singers impersonate Tom Waits?