Audio and visual monitors for your baby might be useful in very few situations. For example, you are in your yard and you want to hear when your baby awakens from a nap. Or your home is multilevel and you think that you really will not be able to hear your baby awaken or cry. But the truth is that monitors are rarely needed. The sleeping brain of the mother is acutely sensitive and discriminating to her baby's cry. Even a quiet cry is like an alarm bell going off in her head. A louder but distant siren will usually not awaken the mother because the brain recognizes that there is no close danger.
Audio monitors robs mother of deep long sleep because it amplifies very quiet sounds that do not need to be attended to. The visual monitor can make a parent compulsively watch their baby when there is no real need for watching. Monitor companies prey on the natural fears of new parents.