5. Very Natural: almost indistinguishable from a real person; pronunciation, intonation, and rhythm are completely natural.
4. Mostly Natural: Slight awkwardness in places, but overall sounds like naturalhuman speech. No problems understanding the content.
3. Somewhat Unnatural: Some elements of pronunciation or intonation feel artificial, but the message remains clear.
2. Unnatural: Rhythm or intonation is noticeably off. The speech does not resemble a real person's voice and may be uncomfortable to hear, though still understandable.
1. Very Unnatural: Both pronunciation and intonation sound artificial, and comprehension may be challenging. It does not resemble human speech at all.
