It sounds like urban legend: “Hacker hacks video baby monitor web cam and screams at little girl.” But it’s true, and it happens more often than you think, primarily owing to people putting their baby monitors web cams online and never changing the default password.

A new study has determined that baby monitors, microwaves and wireless television transmitters have the effect of jamming and slowing down wireless Internet access. In fact the study, conducted by Mass Consulting, found that baby monitors, wireless audio and video transmitters, and microwaves are the primary cause of wireless interference and access issues, not people using excessive amounts of bandwidth as previously thought.