Baby Monitors
If you’re out of the hearing range of your baby, a baby monitor is a must-have. Many include dual-radio technology, parent talk-back, soothing music to play to the infant, and a separate video channel. They faithfully record sounds and videos of the baby and allow for rapid parental response.
The predecessors, which were used in the same capacity, were entirely mechanical and looked it. They also gave off a rather sinister vibe.