Why the children voice generated has a buzzing noise?

[tan90xx]

May I ask why the children voice generated has a buzzing noise?
The reference audio is 'child2.wav' and I followed the inference guide exactly. (If you need to check, please change the extension from .mp4 to .wav.)

Reference Text：我在家里睡就不会被打搅了，我先吃一口嘛，就想吃一口一小口，我又可爱又有责任感，我到底犯了什么错 别以为一根棒棒糖就能弥补我受伤的心灵，起码得两根！
Target Text：原来这就是彩虹宝藏！糖糖看着自己发光的爪子惊呼。栗栗的橡果项链变成了彩虹宝石，朵朵发现绘本上的水晶贴纸正在口袋里发烫。他们手拉手转圈圈时，森林里所有动物都循着光芒聚拢过来。

child2.mp4

fake_0.mp4