As Meep says, it's very likely that your rat population will decide that the new 'soundwave system' is an irritation that they can live with. Rats are very smart! Let us know how it's working as time passes. Mary
Mint won't hurt your chickens, and they don't like many flavors and so may not eat it anyway. Expecting it to repel rats isn't likely to happen either. Some rats may fall for a live trap, although none ever did here. Kill traps that are only accessible to the rats might get a few, but only...