The mice themselves: quieter than you can hear
A large part of mouse conversation happens in ultrasound — squeaks and songs pitched above what human ears can pick up. At the frequencies we can hear, a healthy mouse going about its evening is close to silent: the pad of tiny feet, the whisper of bedding being moved. Nobody has ever been kept awake by a mouse's voice.
What owners hear, and occasionally complain about, is the mouse's environment being used at full energy, at night.
The wheel, the bars and the bedding
Mice are most active at dusk and through the night, and their peak energy lands squarely in the hours a house is trying to sleep. The main offender is the exercise wheel: a cheap wheel with a loose axle squeaks or rattles with every revolution, and a mouse runs for miles in a night — thousands of revolutions of rhythm section. Second is gnawing: mice must chew to wear down their ever-growing teeth, and cage bars, plastic fittings and wooden chews all produce their own small percussion. Bar-chewing tends to peak just after lights-out, when the colony first wakes and looks for something to do. Third is architecture: digging, tunnelling and hauling bedding around an enclosure has a constant soft rustle to it.
Location amplifies everything. An enclosure in a bedroom, on a wooden surface that acts as a sounding board, will sound twice the size of the same setup resting on carpet in another room.
The fixes that work
A well-made solid-surface wheel, mounted firmly or standing level, removes nearly all of the noise problem in a single change — it is the upgrade mouse owners praise most. Give the gnawing a legal target: applewood sticks, cardboard and wooden chews in rotation mean the bars mostly get left alone. Rotate those chews every few days, because a bored mouse returns to the bars. Deep bedding absorbs the digging sounds as well as delighting the mice. And if anyone in the house sleeps lightly, the colony simply lives outside the bedrooms; mice neither know nor care which room hosts them, as long as it is draught-free and out of direct sunlight.
When a mouse sound is a message
There is one important exception to the rule that mice are silent: a mouse you can hear vocalising — audible squeaking or chirping, or clicking and crackling as it breathes — may have a respiratory problem, which is the commonest illness in pet mice. A mouse that sounds noisy in itself, especially alongside sneezing, a hunched posture or a dull coat, needs a vet promptly; breathing trouble in something this small does not wait.
Treat any change in the soundscape the same way: the equipment sounds are background, while a new sound from the animal itself is a signal. If the sound still will not resolve into one camp or the other, put a follow-up question to KinsLe's Kinny; he answers using the KinsLe Answers library.