Is Speech Synthesis protected by copyright or patent law? What does Mac OS License protect?

I know that according to a question asked by another user here https://apple.stackexchange.com/questions/43290/are-the-apple-text-to-speech-voices-copyrighted > "No other use of the System Voices is permitted by this License, including but not limited to the > use, reproduction, display, performance, recording, publishing or > redistribution of any of the System Voices in a profit, non-profit, > public sharing or commercial context." But what is that License? Is it a patent or is it copyright? What kind of protection does the license include? At what point do these protections actually limit use? I am considering Radiohead's Fitter Happier song for instance.