The best monitor for sound in our tests is the Philips Avent SCD630, with a score of 8 of 10. This monitor has the best sound activation and background cancellation features in the group, and while the sound is bright, it is also clear without an echo. Most of the competition earned 4s and 5s for sound, with all of the Wi-Fi monitors only earning 4s. It seems that no matter how good your parent device might be, the Wi-Fi cameras struggle for the most part to transmit clear sound with good sound features.
Frequency: Some baby monitors operate on the same 2.4GHz frequency band as household products like microwaves, cordless phones, wireless speakers, and so on. When the monitor is on the same frequency as a number of other products, you can experience interference and static. You may want to get a monitor that uses a different frequency like 1.9GHz, which the Federal Communications Commission sets aside for audio-only applications. It's called DECT, or Digitally Enhanced Cordless Telecommunications.
While the price is too high compared with our other picks to merit a recommendation, the Arlo Baby by Netgear Smart HD Baby Monitor and Camera does have some appeal, mostly because it overcomes some of the traditional shortcomings of Wi-Fi monitors and security cameras used for that purpose. Its main advantage is that its app can continue to play audio even if the app is not open in the foreground of your mobile device. This means it can continue to broadcast sounds from a baby’s room while parents sleep elsewhere, alerting them if there’s trouble (as a traditional monitor would), without the hassle of loading the live stream every time. It also offers some unique features: The camera itself can work wirelessly off a rechargeable battery (which no other monitor we’ve tested can do), and it can track and chart several days’ worth of temperature and other environmental data in a child’s room. These features alone don’t justify its added cost—the current price is about $100 more than that of either our pick or the least-bad Wi-Fi monitor we’ve tested—but that cost may be easier to swallow if you’re already using other Arlo devices, which we began recommending as a runner-up in our piece on indoor security cameras in fall 2016. As with most Wi-Fi monitors, owner reviews note problems with the signal dropping out, sluggish response time when opening the video on an app, and other irritations, such as problems seeing the feed on multiple devices.
Wireless encryption: This ensures that no one else can tap into your monitor’s “feed” and see what’s going on in your house. WiFi-enabled monitors are great for portability and range, but may be more susceptible to hacking. If you go this route, be sure to secure your home wireless network and keep the monitor’s firmware updated. Otherwise look for digital monitors with a 2.4 GHz FHSS wireless transmission.