Can you "spam" bird sounds so that birds no longer interpret them right?
This is at least doing some confusion, probably also harm. A lot of wildlife conservationists warn about using smartphone apps which replay bird songs, as they are confusing the animals. An example is the Dorset Wildlifetrust.

This phenomenon has even be analyzed scientifically, and the results show that birds are irritated. Territorial birds seem to be affected more and it has been shown that, when a fake call was replayed to them, they sang more often and longer. In the first paper they speculate that this will drain too much energy and prevent the birds from doing other important things.

The second paper looks at zebra finches, which are not territorial. Here they find that birds pay less attention, the more often the song is replayed.
The articles:


Simulated Birdwatchers’ Playback Affects the Behavior of Two Tropical
Birds
Habituation in songbirds.