Of the three types of baby monitors in today’s market, audio monitors were the first and original type to be available on the market. They can be either analogue or digital depending on what model you choose. They function by transmitting a signal from the monitor in the baby’s room to where the parent’s monitor is located. These monitors are the least expensive but also have a limited range in distance. The distance will be governed by the quality of the unit you purchase.
The primary use of audio monitors is to allow parents to hear if their baby is still asleep, just woken up or unsettled.