I got both of them on video howling together. It's hard to hear them over the siren, but it's rare to hear them howl any other way. I had to sneak out the door to video them, as you can see, they quit when they saw me.
BTW, our town also uses the tornado warning siren for volunteer fire department calls, it's in the city park a block away. That's why it's so loud.
That is cute! My brother's Dobie used to live way out in the country, where they rarely heard sirens. When he moved into my Mom's house, he heard sirens on pretty much a daily basis. He would run around the yard howling his head off every time there was a siren of any kind. We always wondered if he was just joining in, or if they hurt his ears or scared him.