Toddler is sound sensitive

my toddler is definitely sound sensitive. sudden, loud noises scares him. people cheering, another child screaming, fireworks, etc. first, he covers his ears and dives into my lap. if the noise continues or happens again, he then begins to scream and cry uncontrollably. he will continue this until the sound, or himself, is removed. now i am hard at hearing so any loud noise does overwhelm me and cause a slight internal panic until its removed. beacuse I am hard at hearing, it overwhelms me as my world is usually pretty quiet compared to others. for this reason, we do tend to steer away from sudden, loud noises if possible.

do you think this is a learned behavior or developmental delay?

let me add that this is the ONLY symptom he experiences that is commonly found in individuals with autism. his doctor, and myself, do not believe that he has autism.