I have this very bad......I have a service dog now to help me cross the street.....as most people have "fight or flight" when startled usually by loud noise(not exclusively) I freeze....

I did not catch if your using any hearing protection?...I use noise cancelling ear buds 100% of the time in public and if by traffic the buds are switched on to lower all the outside noises....

Mine has never improved but my over the top reaction has lessened...

I also found out my startle reaction is cumulative.....I get edgier and edgier and takes less and less to make me feel worse...This took me years to figure out!