[mwcampbell]

Yes, the screen reader output will probably interfere with your speech recognition. You may be able to work around that on some platforms by enabling echo cancellation when getting mic input from navigator.getUserMedia, but I don't know if that actually works on any desktop platforms.

In general, you should assume that the user already has whatever assistive technologies they need, and you don't need to provide your own, just make the content and UI accessible using semantic HTML and (if needed) ARIA. Providing your own screen reader, for example, would definitely be a mistake. The same should ideally also hold for voice control, but apparently you're actually getting some demand for that.