The audio quality is excellent, thanks to VTech's use of DECT 6.0, so you shouldn't hear any interference, static, or echoing when you listen in on your baby. Since the monitor uses a special frequency to relay the signal from the monitor in your baby's room to the parental unit, everything is encrypted and secure. No one but you will hear your baby.
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.