Since babies sleep a lot and new parents can't stay in the room with a baby the entire time, the baby monitor is a great way to listen for sounds of distress from the child. A baby monitor is a device that sends sound over a one-way radio frequency to a receiver. The distance the sound is projected varies between different models. Most baby monitors are built to work within a distance of about 150 feet. The transmitter is placed in the room with the baby and should be plugged in no more than 10 feet away from the crib. The receiver is usually portable and carried around with the parent throughout the house and outside on the porch or in the yard.
The radio frequency used to transmit sound from the baby to the caregiver is the same frequency used for cordless telephones and other transmissions that can come from police and emergency signals. More expensive models are built with higher frequency abilities that can eliminate outside interference. Baby monitors used by neighbors also can provide interference in listening to a child in one household. Monitors that come with a scrambler can minimize and remove any outside interference. To work, baby monitors must be turned on at both ends. Less expensive baby monitors that run on batteries may leave parents under a false impression that they are secure in their ability to hear when the baby wakes up.
Look for features that allow the baby monitor to work through any number of scenarios. Monitors such as the Evenflo Monitor and Intercom are usually less than $80. They beep when the battery is low and provide an option to turn the sound down and display noise by emitting a flashing light, which may be useful when parents do not want to disturb others in the room. The Evenflo model also features a two-way sending option that allows parents to speak back to the child, sometimes soothing the infant back to sleep. More advanced baby monitors come with video displays that send pictures to the receiver over a digital wireless signal. Audio/video baby monitors such as the Babyview20 by Levana run closer to $200. High-speed microprocessors are built into the latest baby monitors that are placed under the sleeping baby and detect movement. If the baby stops moving for more than 20 seconds, an alarm sounds. Movement detection monitors such as the Babysense V from BabySafe also include the traditional sound monitor and cost about $100.