You have to slightly tense your vocal cords and raise the back of your tongue, so I suppose there's a minuscule amount more energy. I have no idea how you'd measure it, or if it's even measurable. It's certainly not something you notice or are consciously thinking about.
By that measure, I suppose certain phonemes require slightly more energy than others. Any kind of stop or fricative for instance requires more muscles coming into play than uttering a vowel, since vowels are unrestricted. Again, the difference is so small as to hardly be noticeable.
If that's true, then maybe different accents or dialects of a given language have different proportional energy use. Sounds like a good linguistics doctoral thesis if you ask me.
Chinese uses pitch and tone much more than English. Would you say rising tones take more physical energy than falling ones in either Mandarin or Cantonese?
As for the speech-to-text, I don't really use it so I can't say. I'd imagine most native speakers would, simply because that's how we're used to asking yes/no questions. Whether it's strictly necessary for speech-to-text, I can't say.
