What the dog does is react to any noises (because the owner is totally deaf and won't hear them).
These include:- door bell, alarm clock, your mobile phone (for texts), smoke alarm, oven alarm (so you don`t burn your pizza), your baby crying, emergency vehicle sirens and as shown in the film, someone else can send the dog to get your attention (if you`re the one who`s deaf) cos obviously calling for you won`t work.
Plus as someone pointed out, it`s a chick magnet.
As for him having an accent, that`s entirely possible. Search for Bone Anchored Hearing Aid on google to find out how your hearing can be improved in cases such as his.
The charity featured isn`t that far from my parents; they often look for puppy sitters for dogs who are still too young to begin their training. Labradors are an excellent breed for this sort of thing due to their nature.