Text to Speech features converts written text to audio. Instead of reading, readers now have the option to listen. This a eventually improves user accessibility.
Does Text to Speech helps is SEO?
The answer is NO. Text to speech features does not help in Google search engine but it contributes to better overall experience for user. So, should you enable TTS in your website? The answer is YES, as this features allow user to stay longer in website thus creates real traffic to your website.