I'm terrified by the amber alert noise
What happens when you hear the noise?
I always freeze up on the words "missing person" on television
It is sad to know that people are missing but you shouldn't let that terrify you. It will not hurt you and it will just cause a lot of anxiety when you hear a similar noise.
I just hate the noise and it gets on my nerves.
Are you sure there's not some sort of underlying trauma that brings this response up?  Perhaps you should consider talking to a therapist if you're having such a strong emotional reaction to stimuli like that?