Like Doberlover, I would let Ava bark a few times before I would say 'enough' in a firm tone. Once she realized I wasn't going to let her way, she'd stop but it did require a lot of patience on my part. It didn't take her long to figure it out but when it's 2 am and you have to wake up in a few hours, it became VERY tempting to give so she'd keep quiet.