Yes, I agree with Domingos. Kerstin Probiesch has also written an article about this, although this also heavily emphasizes the case in PDF documents. The problem is that, for the screen reader to switch the language, one voice has to stop mid sentence, switch the voice to one that speaks the other language, speak the word or phrase, then switch back, which can take half a second each. It ruins the whole sentence melody, sounds as if you were to take a breath in mid sentence, disconnecting the words in a very unnatural manner for no apparent reason. I find it quite annoying if it happens too often. I tend to switch off language switching for that reason. Full sentences or paragraphs are no issue, single words in a sentence quickly become a huge annoyance.