Loud noises can be scary to small people, especially when they are unexpected. I read somewhere that it is helpful to warn them (if possible) of the upcoming noise so that they can mentally prepare for it, and that this makes it less scary.
It was quite obvious that Mia was scared by loud noises early on, so we started telling her (“Mia, I’m going to make a loud noise now”) and also making the sign for loud noise. That process helps immensely. Her reaction is pretty cute and it is clear she knows exactly what it means.
Yesterday morning, I realized I had the perfect opportunity for catching her reaction on video: http://youtu.be/JlIKBoqwez8
Of course, unexpected loud noises are impossible to avoid. When that happens, she will grab tightly onto me or Papa or whomever is nearby. Still we can at least explain the noise after the fact, which seems to help.