I was born in Castile, so I usually speak "accentless" standard Spanish, but my mother comes from Extremadura, just a couple hours drive to the south, and when I speak to her I involuntarily switch to the extremaduran accent. I don't notice it but other people hearing me for the first time are shocked by the sudden switch.
Extremaduran accent has the same aspirated x and s mentioned in the article, so for "This is Extremadura" I'll tend to say "Ehto é Ehtremaura" to my mother and "Esto es Extremadura" to other people. Another curiosity is that many of the original "conquistadores" (Cortés, Pizarro) hailed from Extremadura.