I have been trying to capture this moment on video for months without any success until now!
Every time Dingo hears a fire engine or police siren he goes into 'hi alert mode'. It's so funny to watch him run around the house and yard baying in response to the piercing noise. The problem with capturing it on video is once he sees he's got your attention he stops baying, almost as if he's passing the problem on to you. I was lucky enough this time to sneak up on him to capture him in the act.