If the sound from the camera in the baby's room exceeds a set threshold (for example, if the baby is crying), the parental monitor will receive an alert to let you parent know that your child is crying. There is no sound alarm on the baby camera.
Then you can talk to the baby through the two-way intercom feature to soothe your baby.
About white noise and lullabies, white noise is played to the tired parents on the monitor side and lullabies are played to the kids on the camera side.