Accept the chorus, manage its edges
Dawn and dusk calling is hardwired flock behaviour for a cockatoo. In the wild the flock calls to confirm who survived the night and to gather before roosting, and a pet cockatoo does the same to its human flock at first light and again as the light fades. In a terraced house with thin walls you cannot eliminate that twice-daily chorus without harming the bird's welfare, and trying to punish or ignore it into silence usually makes it longer. What you can do is shape everything around the calling: when it starts, how long it runs, how much of it reaches the party wall, and how your neighbours experience it. Owners who succeed treat this as sound and routine management, not behaviour correction.
Morning: predictability shortens the dawn session
Cockatoos call longest when the morning is uncertain: light leaking in at uneven times, people moving about without acknowledging the bird, and breakfast arriving at random. Fix the sequence instead. Uncover or light the room at the same time each day, greet the bird calmly and promptly, and make the first food of the day a foraging task rather than a filled bowl: pieces tucked into a cardboard forager, a skewer of vegetables, or food scattered through shredded paper gives beak and brain a job that competes directly with calling. Let the bird out for social time soon after, because contact calling drops sharply once the flock is actually together.
Evening: a clean wind-down into real darkness
The dusk session runs best when it is allowed to happen once, at a predictable time, and is then followed by genuine night. Dim the room gradually, offer a final social period and a small evening feed, then cover the cage fully or move the bird to a dedicated sleep cage in a quieter room for the night. Cockatoos need a long stretch of uninterrupted darkness to sleep well, and a bird that is kept up under bright lights and television noise until late will often call in repeated bursts and start the next dawn overtired and louder. Keep the sleep space away from streetlight spill and household traffic, and keep the cover-down time consistent even at weekends. If the evening calling is escalating rather than settling over several weeks, or the bird is also plucking, eating less or showing changed droppings, discuss it with an avian veterinarian, since discomfort and illness can sit behind a change in vocal behaviour.
The terraced-house sound kit
Work on the room as well as the routine. Place the cage against an internal wall that is not the party wall where the layout allows it, and if the cage must sit near the shared wall, put bookcases, curtains and soft furnishings along that wall to absorb sound rather than hard surfaces that reflect it. A rug under the cage stand and a cover used only as part of the sleep routine both take the edge off volume without isolating the bird during the day. Keep windows on the party-wall side closed during the peak calling windows in warmer months, when open windows undo all the indoor softening at once.
Neighbours are part of the plan
In a terrace, goodwill is soundproofing you cannot buy. Introduce the bird before problems arise, explain that there will be a short chorus at dawn and dusk, and give neighbours a way to tell you if a particular time is especially difficult, such as a night-shift sleep pattern you could be extra careful around. A brief conversation and the occasional apology after an unusually loud morning preserve far more tolerance than silence and surprise do. With routine, room and relationships all managed together, most households find the calling settles into a short, predictable feature of the day. Dividing the dawn forage preparation, the evening wind-down and the sleep checks between the people at home with KinsLe Care Teams keeps each step happening at the same time daily, even when work patterns change.