I also don't think what you say really counts.
But how you say it does.
I talk to my birds all the time. My boyfriend has got use to it by now, but I'm sure in the beginning he might have found it weird, although he always said it was nice to see how much I cared for my birds.
Anyways, I use an excited voice when I greet them or want them to be active. When wanting to calm down a bird that needs it (having been scared or something similar), I use a soothing voice. When they do something bad, I use a firm voice.
Really, I guess it's like when talking to kids in different situations
