[qayxc]

Natural language is a bit too complex for that I think.

There can't be any universal stimuli simply because there's multiple languages and cultures that don't all have the same response to stimuli.

There's a relationship between neural activity and writing system, for example [0].

Then there's stimuli that activate the language centre in some languages (e.g. click-sounds the Khoisan language families in Africa) but not in others. Some languages (especially East Asian languages like Vietnamese) also use tone to distinguish lexical or grammatical meaning, while Indo-European languages do not. which is another significant difference in (here: verbal) language processing.

All this leads me to conjecture that supernormal stimuli are highly unlikely in this context due to the high-level nature of the subject as well as the differences and the diversity in the involved regions of the brain.

[0] https://www.sciencedirect.com/science/article/abs/pii/S01680...