@mfld Sounds like he is barking due to afraid and nervous, you have help him gain confidence around people and things, let him socialize more slowly, start with people you know but your dog is not familiar with, or people in you neighborhood. And if he is food driven, let them give him some treat you prepare, so that he has a positive impression of stranger.
My puppy tend to bark when people or anything coming towards her, but I keep bringing her out for walk everyday, she will slowly familiar with sound around her, if she get too nervous, I will take her away from that place,, I always allow stranger try to play with her, she will reluctant initially, but I let her choose to continue or go away, she will slowly open to it, my girl is food driven, so that's help also, now she allows everyone to pet her, and won't even afraid of big bus drive pass her.