My lovebird is terrified of the little noise that my computer makes when I adjust the volume. I have Windows 8, and when you make the sound louder or quieter, it makes a little "ding!" He hates that ding! He will shriek at it. Now I plug in headphones before I adjust the volume.
He also hates the notification noise that Facebook makes when you receive a new message. I have to make sure the computer is muted if I get a message, or he screams and hides in the corner of his cage.
I think he had a bad experience with these things, somehow. Maybe his breeder played these noises when giving shots or something? I'll never know. He just really really hates them.