A baby monitor, also known as a baby alarm, is a radio system used to remotely listen to sounds made by an infant. An audio monitor consists of a transmitter unit, equipped with a microphone, placed near to the child. It transmits the sounds by radio waves to a receiver unit with a speaker carried by, or near to, the person caring for the infant. Some baby monitors provide two-way communication which allows the parent to speak back to the baby (parent talk-back). Some allow music to be played to the child. A monitor with a video camera and receiver is often called a baby cam.
At over $200, are advanced audio/video monitoring systems with multiple cameras and receivers with large screens, as well as the ability to connect to several mobile devices. While they are loaded with features, it’s important to look closely at the audio and video quality. Expensive monitors are just as susceptible to interference as inexpensive ones.
We don’t think most people would be happiest with a Wi-Fi–enabled baby monitor. The benefits—primarily, being able to view the camera footage remotely, on multiple phones, without keeping track of a separate monitor—do not make up for the disadvantages Wi-Fi monitors have as a category. Security is probably the first thing on most people’s minds. The likelihood of someone hacking into your baby monitor is remote, but it’s possible, said Mark Stanislav, director of application security at Duo Security, in an interview with The Wirecutter. You’re relying on the security of your own home network and also the ability of the manufacturer to secure all its devices. “Once you get into an Internet-connected device, and it really depends on what kind of device it is, but these devices very often bypass your home’s router and firewall. Basically, once you’re connected to this device, you are inside the home’s network. So, it’s possible to use these devices to access other devices in a home,” Stanislav said. (Stanislav was also involved in Rapid7’s research into the vulnerabilities of Wi-Fi–enabled monitors.)
Watching your child from moment to moment is far more important than going over footage from previous nights, so baby monitors don't usually make a big deal about saving video for later, whether using built-in storage or through a cloud service. They can take snapshots and short clips when they detect movement, but they won't offer time-lapse videos of entire nights at once, or let you page through hours or days of footage. Those features are useful for identifying burglars, but they don't really help you watch your child unless you're in a Paranormal Activity sequel.