I used to work in automotive navigation. Other colleagues handled our voice systems, but I do remember all our prompts were written in SSML[1] with varrying amo

I used to work in automotive navigation. Other colleagues handled our voice systems, but I do remember all our prompts were written in SSML[1] with varrying amounts of specificity. We would use Lua to configure and customize the SSML, including some custom extensions for different voice renderers. Even with the prompts marked up, there were huge differences between products. Some car OEMs would pay higher fees for better voice and some wouldn't. It's fairly tedious work and difficult to scale as the amount of sentences grows. We basically built up a catalog over many years and they were always explicitly stated as part of our requirements docs. Of course the renderers could say anything you wanted but letting it free form was so a big risk from a product point of view. [1] https://en.m.wikipedia.org/wiki/Speech_Synthesis_Markup_Language https://en.m.wikipedia.org/wiki/Speech_Synthesis_Markup_Lang...