I found this because I need to know what a bird can hear that wont bother a person.

Here is an interesting story. In World War One (WWI) Parrots were kept on the Eiffel Tower in Paris, France because of their remarkable sense of hearing. When the Parrots heard the enemy aircraft coming they would warn everyone of the approaching danger long before any human ear would hear it.

Frequently Asked Questions to our Audiologist about hearing and ear related issues

Pet parrots are playing havoc with TV sets - by controlling them with "silent" squawks. The birds mimic ultra-sonic beeps made by remote control handsets, which they can hear but humans can't. The "sounds" turn TVs on and off, and change channels. And owners are fooled into thinking their sets are on the blink... David Wilcox of the World Parrot Trust at Hale, Cornwall, said: "Parrots are able to imitate high-pitched sounds inaudible to people. I know one that imitates a dog whistle that no human could hear. The dog rushes up yapping to find it's been conned by a parrot." - Daily Mirror, 30/9/91

Animal Antics (Do or Die)

That's very interesting Angie. Thanks for posting it. I was thinking that possibly Peanut would respond to a clicker. While not silent, it may not be bothersome to humans when you guys are out in public.

I am thinking of something that he could hear over a distance if I let him fly outside. I let him fly to the aviary but not back again home again. It is only a short flight with a definite goal. I don't have a safe landing place for him to fly back to the house if he misses the door. I have considered a perch across the top of the doorway. He is good about obeying "no fly' but accidents happen. After the accidental fly around the supermarket I need something other than his name.

That's really interesting Angie- thanks for posting!!!