loss get larger when i set batch size to 256

[yujack333]

Hi, it great job. But i meet some problem when i train with Mutiple GPUs. when i use 4 gpus to train and set the batch size to 256 in train.yaml. the Pitch Loss get 200~400 and the tone is not the same as the speaker. Using single gpu(batch size set 16) to train is ok. Do you have any idear for this problem? do i need change any other parameter when i change the batch size.