Quieter than most conures, not quiet
Among conures, the green-cheeked is one of the least noisy, which is exactly why flat dwellers ask about it. It does not produce the sustained, ear-splitting screaming of a sun or jenday conure. What it does produce is frequent chatter, whistles, grinding beak sounds at rest, and sharper contact calls when it hears you arrive home, when the household wakes, and as the light fades. In a flat, where a neighbour's bedroom may share the wall behind the cage, those repeated calls at unsocial hours are the whole question.
When a flat-kept conure is loudest
Expect two predictable peaks. The first is early morning, when a conure that has slept in darkness greets the day and calls to its flock, meaning you. The second is late afternoon and evening, a natural flocking and settling period. A bored conure left alone in silence for long working days may also learn that calling is the one behaviour that eventually produces a human, and that learned pattern is much harder to live beside than the natural dawn chorus.
Reducing the risk to your neighbours
Cage placement does more than any training trick. Put the cage against an interior wall, not the wall shared with a neighbour's bedroom, and keep the bird's main living space in the room you actually use so it is not calling to reach you. A consistent long night in a darkened, covered cage or a separate sleep cage steadies the morning peak, because a conure kept up under bright lights until midnight tends to be tired, wired, and vocal the next day. Rotate foraging toys so the bird works for food during the day, and answer contact calls with a quiet whistle from where you are instead of rushing in, which teaches the bird that a soft call gets a reply too.
Check the building before the bird
Read your lease or building rules for pet and specifically bird restrictions before you fall for a chick in a shop, because a noise complaint can force a rehoming neither you nor the bird chose. Be honest about your walls: modern insulated blocks and older thin-walled conversions are different propositions for the same bird. If neighbours are approachable, telling them a small parrot is arriving and giving them a way to reach you directly often prevents a first complaint becoming a formal one. If you already know sound travels clearly from next door into your flat, assume your conure's calls travel just as clearly the other way.
When flat life is not fair on the bird
A conure that is shushed, covered for long stretches of the day, or banished to a spare room for making normal parrot sounds is paying for a housing mismatch with its welfare. Persistent screaming beyond the usual peaks, feather damage, or a bird that calls frantically whenever you move can signal loneliness or anxiety rather than naughtiness, and an avian vet or parrot behaviour adviser is the right next step. If the building truly cannot absorb the noise, an early, planned move to a suitable home is kinder than waiting for an eviction-style crisis.
Why the sleep routine belongs in the bird's record
A flat-kept conure often settles because its household built a specific pattern: cover time, cage position, a quiet reply to contact calls. A new owner who does not know that pattern may undo it in a week and conclude the bird is a screamer. Keeping those details with the bird prevents that, and KinsLe Transferrable Profiles passes a conure's sleep routine, trigger sounds, and settling habits on to its next owner.