Hearing phantom baby cries is totally normal, and probably results from a new parent's highly-alert, overly tired brain being wired to hear a crying baby.
Baby Crying Sounds - What Do Different Cries Mean? - Petit Journey
Overstimulation: babies and children
Cry-It-Out Method for Sleep Training Explained
Baby crying: Why babies cry so much
Why Do Babies Cry in Their Sleep? How to Soothe a Newborn
Phantom Cry: Why new parents are hearing their babies cry even when they aren't
What if baby doesn't cry after birth?
Understanding your crying baby
Does Your Child Cry All the Time? This Might Be Why - Your Kid's Table
Crying Baby: 11 Reasons Why Babies Cry and What to Do
Did you leak when you heard a crying - La Leche League USA
Is It Normal to Hear Your Baby Cry When They're Not?
5 Reasons Why Your Baby Might Be Crying, and What To Do – Bubzi Co