How to set up a quiet nursery: what makes noise, and how to read the figures

A nursery tends to collect machines. A purifier goes in, then a humidifier, then a fan for summer, and perhaps an air conditioner in the window. Each one was bought as "quiet", and together they can make the room louder than any of them suggested on its own. This page starts from the room. It explains what makes noise in a nursery, which figure on the box to read, and what to check for lights, beeps and locks. Our buying guides then compare the products one category at a time.

We cover noise only. We make no claims about babies, sleep or health, and for anything to do with safety, follow the maker's manual and warnings.

The reference points

There is no official noise figure for a nursery. The ones that exist are the same as for any bedroom:

• Bedrooms at night. The World Health Organization's community noise guidelines recommend less than 30 dB(A) in bedrooms during the night.
• Everyday sounds. The US National Institute on Deafness and Other Communication Disorders puts whispering at 30 dB and a humming refrigerator at 40 dB.
• Loudness. The National Park Service says an increase of 10 dB causes a doubling of perceived loudness. So 40 sounds about twice as loud as 30.

The WHO figure describes the whole room. A maker's figure describes one product, at a distance the maker almost never states. So the two cannot be matched exactly. Use the reference point as the line to get close to, and the maker figures to compare products with each other. For the same points room by room, see how quiet is quiet enough.

What makes noise in a nursery

The air purifier. It often runs all day and all night, which makes its lowest speed the figure that counts. Our guide to the quietest air purifiers for a nursery quotes each maker's lowest-speed figure with the setting behind it, and reads the manuals for what matters once a child can reach the unit: what the child lock covers and whether it survives a power cut, how the filter door opens and whether the fan stops, what makers say about tipping, cords and clearance, each maker's ozone statement, and every light and beep at night.

The humidifier. Mist models have no fan and are close to silent apart from bubbling or a pump starting. Evaporative models have a fan, and their noise changes with speed. Our guide to the quietest humidifiers for a nursery explains that trade-off, notes that few makers say how they measured and several print no figure at all, and covers sleep settings, humidity targets and why a humidifier gets louder.

The fan. A fan is judged at the speed it runs on after the lights go out. Our guide to the quietest fans for sleeping compares tower, box and ceiling fans each within their own type, and reads the manuals for what each sleep mode really does, which displays go fully dark, and which sleep modes silence the button sounds.

The air conditioner. In a window, the figure at the night setting matters, and so does what the unit does between settings. Our guide to the quietest window AC for a bedroom sizes each pick to the room, compares figures only at the same named setting, and flags energy saving modes that stop and restart the fan through the night. For a wall-mounted system, our guide to the quietest mini-split for a bedroom ranks by the indoor head on its slowest fan speed, the part that hangs in the room, and keeps it apart from the outdoor figure.

The dehumidifier. The quiet-looking figures in this category belong to units that remove very little water. Our guide to the quietest dehumidifiers shows which makers name the fan speed behind their figure and how to check capacity claims. Where a room needs one, running it during the day and switching it off at night is one option.

A mini fridge, if the room has one. A fridge switches its compressor on and off through the night, which a steady figure does not capture. Our guide to the quietest mini fridges explains how compressor, thermoelectric and absorption fridges each sound, why most brands publish no figure, and how placement causes rattles.

The baby monitor. It has its own sounds and lights too. We do not cover monitors, but the same questions about lights and beeps apply.

Why the night figure is the one to read

Makers quote their quietest setting. In a nursery that is not a trick, because the quietest setting is the one that runs for most of the night. The catch is that each maker's quietest setting is a different thing: low fan, a named sleep mode, a quiet mode, or no setting named at all.

So read the setting before the number. A low-speed figure from a table that also lists the high speed tells you the most. A bare "as low as" figure tells you the least. And read what the night mode does in the manual. Our guides found sleep modes that start on high for the first hour, raise the speed when the room warms, or switch the fan to Auto. A fan that is silent and then starts is easier to notice at night than one that runs steadily on low.

A quiet room at night is also a harder test than a living room in the day. There is no television and no traffic of people to cover a click, a hiss or a pump starting.

Lights and beeps at night

A lit display in a dark room and a beep at every button press matter more here than anywhere else in the house. Before the first night, check four things in the manual for each machine:

1. Can the display go fully off, or only dim? Some turn off in sleep mode, some after a minute without use, and some only dim.
2. Do the buttons beep, and can the sound be switched off?
3. Does a filter or tank alert beep, or only light up?
4. Is there a night light, and is it off by default?

Locks

Every pick in our nursery purifier guide has a child lock or control lock, and other machines may have one too. The locks differ in what they lock. Some lock every button, some only the speed button. Some undo themselves after a power cut or when the unit is plugged back in. Our nursery purifier guide sets out what each lock covers in the maker's own words. For any other machine, check the same two points in its manual: what the lock covers, and whether it stays on. For anything beyond that, follow the maker's manual and warnings.

How to read a maker's figure

• dB or dBA. dBA, also written dB(A), is weighted to follow how people hear. Many makers print plain dB. Do not rank a dB figure against a dBA figure. See dBA explained.
• The setting. Which speed or mode does the figure describe? If the maker does not say, treat it as the quietest.
• The distance. Makers almost never state it, and OSHA notes that indoors, sound falls away more slowly than in open space because it reflects off surfaces. That is why brand-to-brand gaps of a decibel or two mean little. See why you cannot compare dB ratings across brands.
• The unit. Bathroom fans and range hoods use sones, which are not decibels. See sones vs decibels.

Use the figures to compare products with each other, within one maker's sheet where you can. Do not use them to predict what a meter would read in your room.

A short room checklist

1. Find the loudest machine. The loudest machine usually sets what you hear, so start there.
2. Read the night figure. The lowest speed or night mode, with the setting named.
3. Size up and run low. A unit rated for a bigger room can run on a slower, quieter speed in yours.
4. Check the night mode in the manual. Does it ramp up, switch to Auto, or restart the fan?
5. Turn off what glows and beeps. Displays, button sounds, night lights.
6. Check the locks. What each one covers, and whether it survives a power cut.
7. Set it down firmly. A level, solid surface avoids rattles, and the manual gives the clearance.
8. Follow the manual. For placement, cords and use around children, the maker's manual and warnings come first.

We did not measure any of these products. Every figure in our guides is the maker's own, quoted with the setting it describes.