How to discourage unwanted sounds

This is Daisy. She has learned an ear piercing shrill call that she emits when a stranger walks in or when she is stressed. This is her way of announcing that she is anxious.

Can this be discouraged? One suggestion is to "desensitize" her to as many "scary situations" as possible. If people coming into her area are worrisome, spend an afternoon having drop-ins stop by. Pre-educate them to walk in without making any eye contact and sit down facing 3/4 away from her. With their eyes downcast, have them talk or sing to her using her name. She will slowly become more comfortable with "strangers". This, obviously, takes some commitment to arrange.

Another suggestion would be to calmly respond to the shrill call with a reassuring "counter call" that she may take on as a self-soothing murmur. Many birds learn to announce, "You're okay" when they feel uncomfortable. My birds announce this when a guest bird seems agitated or ends up on the floor.