Quiet enough for thin walls
For flat living, the relevant question is not whether zebra finches make noise, because they make it constantly, but whether that noise escapes your rooms. It does not. A zebra finch's voice is built for close flock contact across a few metres of grassland, not for carrying across a landscape, so its beeps, peeps and nasal honks register at the volume of quiet conversation and fade to nothing through a closed door, let alone a party wall. Keepers in flats report that visitors in the next room cannot tell birds are in the home until they see the cage. Against the sounds that actually generate neighbour complaints, barking, music, a screaming parrot, finches are effectively silent.
What the flock sounds like all day
Inside the room, be ready for a soundtrack rather than silence. Males sing a rhythmic song of beeps and buzzes, learned from their fathers and unique to each bird, and an excited male sings it many times an hour, especially in the morning and whenever something changes in the room. Females answer with contact calls, youngsters beg with rattling cries, and the whole flock comments on feeding, bathing and disputes in a continuous low chatter. At dawn the volume rises briefly as the birds wake and greet the light, and it winds down at dusk until the room goes dark. Most keepers describe the effect as cheerful background, on a level with a ticking clock or a kettle, and it becomes part of the flat's atmosphere within a week.
The one group that can get louder
Numbers and breeding change the equation slightly. A single pair is gentle; a colony cage of a dozen finches, with several males singing over one another and youngsters begging, produces a busier, more insistent room tone, still wall-safe but harder to ignore while you work. A breeding pair adds the buzzy begging of chicks in the nest, audible across the room for the weeks before fledging. None of this troubles neighbours, but it should shape your choice if your flat doubles as your office and you take calls beside the cage. For most flat keepers, a pair or a small same-sex group hits the sweet spot of lively company without a wall of sound.
Nights are genuinely silent
The feature flat dwellers value most is what happens after dark. Zebra finches roost at dusk and sleep through the night without calling, so there is no finch equivalent of a parrot's dawn chorus blasting at first light on a summer morning; the dawn bout, when it comes, is soft enough to sleep through in the same room for most people. The exception is a night fright, when a noise or a shadow sends the flock bursting around the cage for a few seconds of wing noise and alarm calls. A dim night light near the cage, which lets startled birds see the perches and settle, makes these rare and brief, and keeping the cage away from a hallway door that slams at night removes the commonest trigger.
A flat decision you can make confidently
Of all pet birds, zebra finches ask the least forgiveness from neighbours, and they ask it with a small footprint: a wide cage on a stand, no outdoor space, no walks past anyone's door. Check only that your lease allows caged birds at all, since a few forbid pets outright regardless of noise, and place the cage in the room where you will enjoy the chatter rather than the room where you need quiet for calls. If you keep finches with flatmates, agree early who feeds and cleans so the birds' care never becomes a corridor argument, and KinsLe Messenger keeps every conversation about the finches in one per-pet hub where the whole household can follow it.