Terraced houses share more than a wall. Your dog hears the neighbours' footsteps on their stairs, their front door, their television, and their own dog, all arriving through the party wall with very little muffling — and from his point of view, movement and voices that close are happening inside his home. Handling it means reducing how much trigger reaches him, teaching him a different response to what remains, and staying on decent terms with the people on the other side of the wall while you do it.
Move his world away from the shared wall
If his bed, favourite lookout, or daytime resting spot sits against the party wall, he spends his day stationed at the exact point where every sound is loudest, rehearsing alertness. Move beds and settled spots to an interior wall or the far side of the room, and put distance-creating furniture — a bookcase, a sofa — along the shared wall instead. Soft furnishings genuinely help at dog level: rugs on hard floors, curtains rather than blinds, and a door kept closed between his room and the hall all dull the sharpness of footsteps and voices. Low, steady background sound, such as a radio left on at modest volume when you go out, narrows the contrast between silence and a sudden noise next door, which is often the contrast that sets a dog off.
Teach a quiet response instead of shouting back
When the barking starts, yelling his name across the room usually lands as encouragement — the household has joined the alarm. Let him give a couple of barks at a genuine sound, then calmly interrupt with a cue he knows, ask for something incompatible such as coming to you or settling on his bed, and reward the quiet that follows generously. Practise this first with mild, recorded household sounds at low volume and with knocks you arrange yourself, so he learns the sequence when he is under threshold rather than only rehearsing it at full intensity. If a particular trigger dominates — the neighbours' dog in their garden, their children on the stairs at a predictable time — build training around that specific sound and hour rather than drilling generic quiet in the abstract.
Manage the times you are not there
Leave him with the radio on, curtains managed so he cannot stand at the front window commentating on the street, and something absorbing to do, such as a stuffed food toy, so the first neighbour noise of the morning meets a dog who is busy rather than a dog lying in silence waiting for it. It is worth honestly checking what is actually happening: a borrowed camera for a few days, or simply asking the neighbours when the barking happens, tells you whether you are fixing all-day distress or a ten-minute reaction when next door comes home — two very different problems with different answers.
Stay on good terms through the wall
A brief, friendly explanation that you know about the barking, are training it, and would genuinely like to know when it is worst both buys goodwill and gives you the pattern information your training needs. If their dog barking sets yours off and vice versa, staggered garden times for a while can lower the temperature for both households. Persistent, frantic barking with pacing, drooling, or destruction when left is a different picture from alert barking, and that dog needs help with being alone in his own right, starting with very short absences. On KinsLe, Family Sharing gives the relatives you pick access to his profile, and that access goes to family you have chosen and nobody beyond them.