Hybrid neural translation allows you to take advantage of the quality improvements of neural machine translation (NMT), even if you are not translating both from and to an NMT-supported language. With hybrid neural translation, if one language is only supported by statistical machine translation (SMT), but the other language is available for NMT, you will still see an improvement in translation quality.
In machine translation technology, because of the lack of available training data between any two languages, English is used as a “pivot language” to translate from one language to the other. If you were to translate between two languages, for instance from French to Chinese, in the background the machine translation tool would typically first translate the French into English, and then translate the English into Chinese. Microsoft Translator is no different, whether it is for the traditional statistical or the newer neural machine translation system.
In the example above, since both portions of the translation are powered by NMT, the end to end translation is NMT. However, what happens if only one of these two languages has NMT available?
If you were to use hybrid translation to translate between an SMT language and an NMT one, for instance from Persian into Chinese, the system will first use SMT to translate from Persian to English, but then use NMT to translate from English to Chinese. Since the second portion of the translation is powered by NMT, there will still be a noticeable increase in quality.
Hybrid translation also works if you are translating from an NMT supported language to an unsupported language. If you were to translate from Chinese to Persian, the first portion of the translation from Chinese to English would be NMT-powered, and the portion from English to Persian would be SMT-powered. You would still see an increase in the quality of the end-to-end translation.
You do not receive any benefits from NMT when translating from one SMT language to another.
See the list of supported languages for Microsoft Translator.
Learn more:How does machine translation work (NMT v SMT)?