It sounds like excitement to me. Jasper's still a puppy isn't he? Is your husband the one who does most of the walking, feeding etc? If so, it's probably just Jasper anticipating that something is going to happen and getting wound up.
Your husband could try sitting down again as soon as Jasper starts barking and not getting up until the barking stops. He, and everyone else, will also need to totally ignore Jasper while he's going through this process. Don't look at Jasper, make eye contact or say anything. I know it may take a bit of planning and lots of patience, but the penny should eventually drop with Jasper that barking is unrewarding.
Not sure what you mean about the door. Do you mean Jasper barks when the doorbell goes and gets in the way, making it difficult to get to the door?
My 2 bark at the doorbell, but I've trained them, with the help of treats, to go into the study while I answer the door. I have one who's very friendly and might jump up to say hello and one who's wary of strangers and will growl. Following the changes to The Dangerous Dogs Act earlier this year I could be held liable if my dogs frightened anyone on my property, let alone bite them, so I'm extra careful now when people come to the door. If you could teach Jasper to go to a particular room when he hears the doorbell it will be easier for all of you.
