"Oigo los pasos del bebé."
Translation:I hear the baby's footsteps.
There are a couple of words/phrases, but none of them have quite the same scope as "toddler". The good news is that Spanish speakers are as confused about the possible translation as we are.
I think the answer is the word párvulo, which is essentially a preschooler, and is closest I think to toddler in meaning (un colegio de párvulos is a nursery school), and is also the suggestion given most often in every source and forum I can find.
I thought about this too but I think baby steps has more of a figurative meaning. Here, they seem to be expressing actually hearing footsteps of a baby. Whereas you wouldn't hear the "babysteps" of a major change or undertaking (as in the idiom). I don't know, though. That was the only way I could understand it not being accepted.
I think you're being way too nice in your response. "Baby steps" is definitely metaphorical, is not physical, steps small or otherwise, and as a result is likely to be inaudible, although the baby steps could be the small steps you take in learning how to play an instrument ;)
I don't know how much this differs across regions, but for me, infants are extremely young babies, certainly pre-walking, perhaps even pre-crawling. Babies. on the other hand, can comfortably describe children up until the growth spurt at the end of toddlerhood, when the baby becomes "a young child". (Of course, all meanings are somewhat subjective, but infants and babies aren't precise synonyms as a result.).
(My husband's response is completely different. He's Australian. For him, he would reverse my two definitions.)