I know I am old and have bad hearing, but I thought she said, "La reponse est faible", "The response is weak", not "simple"
It definitely does not come out very cleanly, but i do hear "simple". The vowel "in" (and other nasals) is usually tough to get for learners as it doesn't have an equivalent in English, and i wouldn't mistake it for the "è" in faible, so maybe there is something throwing you off. We can't be 100% sure we get the same audio though, i believe Duo sometimes uses several text-to-speech engines in parallel
What she says is more like "ximple"., starting by a fort consonant sound
I am old as well !