Why is it so easy for men to scare women?

I slightly raised my voice towards one of my female friends who I have known for over a year and she got that scared she ran out of my house. (Keep in mind that this is the first time that I have ever slightly raised my voice towards her). Why did this scare her so much? I am not a particularly intimidating dude. Although I am 6'3 I only weigh around 145 pounds.
Why is it so easy for men to scare women?
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