You might prefer one that has lights as well as sound. All the audio monitors we rated had this feature. The Philips Avent DECT SCD510, which sells for about $120, has a series of small LED lights on the parent monitor. The louder the sound in your baby's room, the more lights go on, so you'll notice his crying even with the unit set on mute. Audio monitors are generally less expensive than audio/video models.
As you’d expect, the talk back functionality and audio quality in general are great—easily better than the crude talk back features on our video monitor picks. With the battery lasting about 19 hours on a full charge, this monitor had the strongest battery life of any in our test (not entirely a fair comparison, as this is the only one with no screen to power). Rated to a range of 1,000 feet, it exceeds the range of our pick (700 feet) both as advertised and in practice during tests.
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.