Speech synthesizers are used in primitive animation intended for distribution in teenage humorous Vkontakte publics: youtube.com
Using voice synthesizers allows you to save on voice acting and creates an additional comic effect due to the combination of monotony of speech with its obscene and erratic content and drama of what is happening on the screen.
A technology like Vocaloid is widely advertised in Japan. This is a synthesized speech that not only knows how to pronounce the words specified by the user, but also knows how to do it with a given measure (rhythm) and according to the indicated notes. Simply put, this technology is able to sing songs (mostly in Japanese).
When I listened to a Japanese song performed in this way, I could not always notice that the voice is artificial (after all, a foreign language affects ). But if we take the English version of Vocaloid, then from the very first words it becomes obvious that this technology cannot yet compete with a real singer.
Despite this, vocaloids have gained noticeable popularity and (perhaps thanks to skillful promotion) even have a lot of fans. Especially famous is such a "singer" as Hatsune Miku. The producers endowed various vocaloids with their own (usually anime, that is, cartoon) looks and gave them names. Each vocaloid sings in its own (different from other vocaloid) voice. Hatsune Miku, in my opinion, is distinguished by a particularly synthetic (unnatural) "squeaky" voice and, perhaps, that is why it is popular. The producers organized several seemingly successful "live performances", where the synthesized voice was complemented by an animated projection of the image of Hatsune Miku on a thin transparent screen in the middle of the stage, creating the illusion of the presence of a cartoon vocaloid on a real stage (the rest of the musicians on the stage were real people and performed the melody on live instruments in while vocaloid "sang"). The concerts attracted an impressive number of listeners.
As for the simpler, "prosaic" areas, the synthesized voice is very important for reading text on the screen. This technology helps people with low vision. I recently read (on the question, by the way) about a blind programmer who actively uses a computer and writes programs using synthesized voice.