barking

i have a yorkie who barks constantly, she barks when i leave the room she barks when i enter the room, she barks at the cats, she barks when she needs to potty, or she just barks to be barking, i have tried ignoring her using a loud noise to distract her but nothing seems to help, i have been told to get a whistle from the pet store (one that only dogs can hear) and use it when she is barking help does any one have any suggestions