There are two basic types: audio and video/audio. Some are analog, others are digital. All monitors operate within a selected radio frequency band to send sound from a baby's room to a receiver in another room. Each monitor consists of a transmitter (the child/nursery unit) and one or more receivers. Prices range from about $25 to $150 for audio monitors and about $80 to $300 for audio/video monitors.
Our favorite standard video monitor, HelloBaby, masters the basic features. It’s the easiest to set up and its video and sound quality competes with monitors twice the price. Its screen is smaller than most, but its simple interface gives you immediate access to the most important functions: talk-back, zoom, and pan; while menu button opens up customizable settings for temperature, sound, lullabies, and timers.
You can get the same system, with a traditional monitor screen that’s slightly smaller at 4.3 inches, for cheaper. If you’re interested in having two zoom cameras or an app that lets you see your baby while away, Project Nursery offers those configurations as well. You can also record video and take photos with it as well (requires an SD card sold separately).
The features we focused on were those we thought either increased the performance of the monitor or made it more user-friendly for parents and increased the odds of getting good quality sleep. We looked for monitors that have sound activation that keeps the parent unit quiet when the baby isn't crying, so parents can potentially fall asleep faster because they don't have to listen to white noise. Some of the monitors were so loud, even at low volumes, that the white noise might keep light sleeping parents awake; this defeats the purpose of having a video product to begin with. We also liked the models with screens that automatically "wake" and/or go to sleep.