Biological explanation, her eyes were squinted when she smiled and the narrow opening of her eyes made it look like she has them closed
Artistic reason, it's easier to draw but when they get serious, you can make them open their eyes wider and make it as detailed as your heart desires
One set of ears is more sensitive in different frequencies and both sets works in different ranges (human: 20-20kHz, cat: 48Hz-85kHz)
so kinda, yeah, in the range where both sets of ears can hear the noise, you can hear 2x as good or more
You do not goon to gender bent characters, especially...