My guess is that "come up" is being used as the opposite of "go down." People often say that they are going to "put the baby down for a nap," or that "the baby has gone down for his nap." The logical opposite of this is for the baby to "come up from his nap" later. So I assume that the machine is telling them that it's time to wake up the baby from his nap (he/she has slept long enough now, so he/she "can come up" whenever the parents are ready). I've never heard this term used this way before, but it does make a certain amount of sense, so I wouldn't be surprised if some people use it.

Angela, wow, I think you are right. Come to think of it, the voice of machine is very similar to that of the real baby who was inside. I thought the machine voice was just one of the signals the machine company made. Thank you! Completely got it.

To me, that sounds like a baby is talking/singing on the baby monitor. That's not the device sounding, that's the child actually saying words. (And that alerts the people to let them know the baby is awake.) * Most baby monitors I'm familiar with are basically just radios - the sounds the baby makes can be heard wherever the other monitor is. (It would surprise me if the machine was making that signal. I really do think it's the kid talking) * Small children (ones that you need a baby monitor for), often make grammatical mistakes. Also, it isn't that important what the child is saying, it is more important that she woke up and someone needs to go care for her.

Thank you for your correction and opinion!

One other thing, Bunch. There is ONE couple sitting on the porch, not two. Two people=one couple. If there were two couples, it would be four people!