Origin of the model name 'Vocos'

Summary

Are there any ancestor or inspiration source of the model naming 'Vocos'?

Detail

I succesfully train the Vocos with other datasets (e.g. japanese), the model is so good.
At first, thanks so much for your great model and its open-sourced code/weight.

Just out of curiosity, why the model is named as 'Vocos'?
The naming Vocos reminds me of "vocoder" or "cosine", but. at least in the paper, there seems to be no description about the naming.