Today, 20% of searches are through voice, with estimations that it will hit “50% by 2020” (Source: ComScore). If you’ve optimized your site for organic search using Schema Markup, you’ve also optimized for voice assistants and Google will take care of speech recognition and NLU (or Natural-language understanding). This was recently announced at Google IO. Google stated that their motivation for schema markup was so that you could optimize content once and be optimized for voice and search.
Google Product Manager, Aylin Altiok, is quoted as saying,
“Focus on building great content using an open standard (structured data) and Google will help you reach your users across Search and Assistants without having to build a custom experience.”
Watch Google IO 2019: Enhance Your Search and Assistant Presence with Structured Data