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Baby monitor jargon buster

By Alison Potter

Discover the difference between a digital and DECT baby monitor and learn why a multi-channel baby monitor could be best for you.

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Looking for a baby  monitor? Don't take a chance on one that could lose signal or is so unreliable you may not be able to hear your baby when they need you. 

We test baby  monitors for battery life and signal strength, and discover whether you'll be able to get on with other tasks around the house with piece of mind. 

Join Which? today  to access all our expert baby monitor reviews and see the best baby monitors on test.


Analogue baby monitors

There are only a few analogue baby monitors still on the market. They tend to be the cheapest option. Analogue-signal monitors are the most open to accidental broadcast, as the signal can easily be picked up on normal radios and other people’s monitors.

Audio-only monitors

As the name suggests, these baby monitors let you listen to your baby. They're usually cheaper than a video monitor. However, some audio-only monitors can sound muffled, making it hard to distinguish between background noise and your baby's breathing.


Battery or dual-powered audio baby monitors

These types of baby monitor run on either the mains or batteries. so you can carry the parent unit around with you when on battery power. The more expensive models in this category have rechargeable batteries. This type of monitor is useful for parents who will be busy in the house or garden while their baby is asleep. 

Rechargeable models save you worrying about batteries running out. However, they are more expensive than mains-powered models, especially if you regularly run a non-rechargeable model on batteries.

22.3 hours The best battery life we've found

Battery indicator

This will beep at you when the batteries are about to run out on the parent unit. Some beep loudly, others just flash a light or display an icon on the screen of the monitor, so you may miss the warning. The worst models simply cut out without warning, leaving you in the lurch.

Belt clip

A simple but useful feature that lets you clip the parent unit to your belt. Some work better than others, though.

Baby unit (or nursery unit) 

Baby monitors consist of two units: a transmitter and a receiver. The transmitter is the part that sits in your baby's nursery and picks up sound from your baby. It's often called the baby or nursery unit. The receiver is the part you keep near you (the parent unit).


Disposable or rechargeable batteries

Some baby monitors come with a parent unit that has rechargeable batteries and a docking station, so you don't have to worry about batteries. Some come without a docking station and you'll have to use disposable or rechargeable batteries. Don't attempt to plug the parent unit into the mains while using disposable batteries, you are likely to permanently damage the baby monitor.  

Which? rates and reviews the best and worst batteries – check out our batteries and rechargeable batteries reviews for the latest long-lasting Best Buys.

Digital and DECT baby monitors

The majority of baby monitors available today offer digital sound. Some models, known as DECT baby monitors, have microprocessors designed to ensure that the only sounds you will be able to hear are those from your own nursery, not anyone else’s. However, this doesn’t stop the transmissions from your own monitor being picked up by somebody else.



Many baby monitors have an array of lullabies to help soothe your little one to sleep. Some of these tunes you can even turn on and off remotely, or via the baby unit itself. This feature may or may not be useful, depending on your baby. Some parents find the lullabies help soothe their little one to sleep, but they won't work for every baby. 

It can be handy to have the option, though. And some pricier models let you play your own music through the monitor.


Mains-powered audio baby monitors

Mains-powered baby monitors are the cheapest option. These come with a parent unit that can be plugged into a socket in any room, but cannot be used with batteries.

As you can't use them away from a socket, they're simple and best for parents who won’t be moving around the house much while their monitor is on, or are only likely to be using the monitor at night.

Read up about cord safety in a baby monitor safety guide

Motion sensor mat

Some baby monitors come with a motion sensor mat. These are marketed as a tool to protect against sudden infant death syndrome (SIDS), also known as cot death. The motion sensor mat detects all your baby's movements, even the slightest ones. You place the mat under your baby, and green lights flash and a tick sounds every time your baby moves. If your baby stops moving for more than 20 seconds, an alarm sounds and red lights flash. Some parents find motion sensor mats really reassuring, however they can cause more worry when false alarms happen. There is no evidence that using a sensor monitor will prevent SIDS. We do not test motion sensor mats.

Multiple cameras

Some video monitors come with the option of adding more than one camera. This is a really useful feature to consider if you are the proud parents of twins or triplets, or have a newborn and a toddler to keep an eye on in different rooms, as you can watch over them all from one parent unit. Most monitors only come with one camera when you buy them, though, so you'll need to factor in the extra cost to buy further cameras.

Multi-channel options

Two channels (frequency bands) should be adequate for most people. You need more than one channel on your baby monitor to help reduce the interference your monitor picks up and improve reception. If you live in a busy built-up area where lots of other parents with baby monitors are in close proximity, creating the likelihood of regular interference, the option of more channels may be helpful.

Our baby monitor reviews assess how clear and distinct the sound quality of the monitor is and check for any interference from other devices.


Night light

This gives the area around the unit a soft glow, which may comfort your baby and can help you see them in a darkened room, so you don't need to turn on the main light and risk waking up your baby. Some models allow you to control this remotely.


Out-of-range alarm

If you wander out of range, an alarm sounds, so you'll know how far down the garden you can go before the signal is lost. 

We test the range of each monitor to see how far you can get outside a house before the signal is lost. We also test how good each monitor is at keeping the signal when moving around a house.

Learn more about how we test baby monitors


Sound-sensitive lights

This is one of the more useful extra features. It means you can turn the sound off and just use the lights as a guide to see if your baby is making any noise. The louder your baby cries, the more lights are illuminated. Not only is this very handy if you are hard of hearing, it's also useful if you have visitors round or are on the phone.

Our lab tests assess how accurate the sound-sensitive lights are and make sure that they increase in line with the volume output, so that you don't miss it when your baby needs you. 


Talk back (two-way-talk)

This intercom-type feature lets you talk to your baby without going into the room. This is great if you want to murmur reassuring words to your sleeping baby, or tell your toddler to get back into bed or that you're on your way, without necessarily going back into the room.

Temperature monitor

Some baby monitors have a digital room-temperature display that shows the temperature in your baby's room. An alarm, either by sound or lights, will bleep or flash at you when the temperature gets too cold or too hot in the nursery. Around 18°C is considered the ideal temperature for a nursery.

While useful, the alarms can get annoying, and some can't be turned off. 


Sleep-deprived parents may want to make use of the range of handy timers a lot of monitors have. The main one is a feeding timer, which you can set for the next feed time, or a sleep timer if you're in a routine. On some models it's also possible to set timers for any light shows, lullabies or night lights, so they turn off automatically after a set period of time.


A handy addition to a baby monitor, so you can check on your baby without turning on the room’s main light.


Vibrate alert

Some models will vibrate to alert you to cries if you have the volume on your unit set low.

Video baby monitor

Video baby monitors let you see, as well as hear, your baby. Most models have ‘night vision’, so you can see your baby in the dark. In the past, we've found that monitors with video tend to have shorter ranges and poorer battery life than audio monitors, but we are starting to see some models on the market bucking this trend.


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