The owner’s behaviour.
Consider how we should cope with any unwelcome behaviour. It is all too easy to scold the dog for being scared of something he cannot understand but this may make matters worse. Likewise fussing and cuddling may make him convinced that he is right to be scared!
It is a hard balance to achieve but aim to reassure and soothe without reinforcing the fear, set a good example by not reacting to the noise and light flashes yourself and try to ignore his fearful behaviour.