The reason specific people can be more triggering is that the reaction "muscle" strengthens and tightens with exposure. There's both a fear and anger reaction f

The reason specific people can be more triggering is that the reaction "muscle" strengthens and tightens with exposure. There's both a fear and anger reaction from a trigger sound. As more exposure happens with a specific person, one tends to start anticipating sounds from them. This heightens the anxiety and makes things worse, as the focus will turn on "when will the next one occur."