am i smart enough

all throughout high school i had good grades and I KNEW i was smart though sometimes i had little obstacles but overall i was a smart girl and knew what i had and needed to do. i am now in college and i honestly have felt like im not smart enough for this, hearing people talk during lectures and hearing the way they speak discourages me for some reason and i feel like IM actually just dumb and i get really sad thinking about it because here all along im not as smart as i thought to be. i also never really studied in high school but (it helped me?) idk why but now im trying to learn how to actually study now while im in college, i honestly just feel like i was not 100% prepared for what it was going to be like.