Last night my almost 3yo male was exposed to the sound of fireworks, was quite close by to our house, and very loud - lasted for about 10 minutes.
This was his first time with fireworks and I was really impressed with him. We were sitting in our lounge room, just relaxing and when the noise started he immediately looked up at me, I ignored him and the firework noise, to his credit he laid back down and went to sleep. I was so happy with his reaction considering how loud they were and he has not been gun tested yet.
It is really important to expose your GSDs to a variety of noises, what are other people's experience with fireworks or really loud noises?