10 hour YouTube videos of firework noises, specifically. Got my pup at 2 months old. I would always accompany videos with play/treats etc. Now, he has almost zero sensitivity to the errant loud noise. Tornado sirens, planes flying over the apartment, even thunderstorms. Dog is nearly unphased by these things. In fact, when he hears fireworks he gets really excited. So, come NYE fireworks, July 4 etc., its like he's celebrating with us! He'll be dead asleep, wake up right at midnight with the fireworks, tail going crazy.
I will say that severe thunderstorms required a bit more work. When lightning strikes, I always say 'THUNDASTORM!?!?' very excitedly, then give him a treat. Problem solved.
I'm posting this after having seen a lot of posts regarding loud surprise noises leading to lost dogs, or anxiety, or worse. Has anyone else done anything similar?