I can understand the sensitivity issue considering the decibels of the sirens but can also see where they can relate to it being like a howl.

Like TashaAnne63, the ones (Labs) did not used to howl and was sort of oblivious to the sirens until I moved next door to one who did, then they would join in with the neighbor's dogs. So in their case, I don't think it was a matter of being sensitive to it but more sensitive to the pack of other dogs. Unlike the Beagle, or Basset who would instantly howl at the sign of even a blip of police or fire siren, could be a sensitivity but in how they howled at so many other things, baying/howling at the moon and talking back howls, hmmm, could be they do relate to it as another howl(?).

The younger ones I have now have never howled either until the wolves began to howl one day in response to the sirens and then joined in as well. This somewhat surprised me because usually their response to the wolves is high alert, hackles up, and silence, listening to them. Instead they run around like nuts when it happens now and join the wolves, as if they were looking for the fire themselves, howling too and sounding just like that mournful wolf.

Either way, it always makes me chuckle. It is a such a different howl, even than the one that is used to, say, bay at the moon or when talking back. Cracks me up but SO hoping it is NOT hurting their ears.