In English, we adults like to say babies go "goo goo ga ga." In French, it's "areau areau." And in Mandarin, it's "ya ya."

So do babies really babble with different sounds in different parts of the world? And what does that tell us about how babies learn to speak?

A few years ago I was on a train, seated across a table from a French woman traveling with her toddler.

His mom and I hit it off and spoke in English for a few hours. Meanwhile, this little boy had a lot to say. I couldn't understand it, but he clearly had opinions about his books, his snacks, maybe how cool it was that his hands were attached to his arms – all in what I just assumed was French.

I said to his mom completely earnestly, "So, what's he saying?" She paused for a while and then she went, "Nothing. He's a baby."

Well, it turns out that baby babble has a deeper meaning.

I called up Megha Sundara, the linguistics department chair at UCLA, whose lab is unlike any lab you've ever heard of. For starters, there's a castle in it. Well, it's a sound booth, but it looks like a castle.

"So the thing about sound booths is they are intimidating spaces," she says. So her student with a background in set design built a castle around it. "And we've never had a problem with the baby going in. They just waltz right in."

Sundara studies how babies listen before they start talking and how they eventually learn language.

When babies first start babbling at around 6 months old, they all make the same sounds – even deaf babies. Then they start to drift toward the language around them.

Babies, it turns out, "are very good at imitating the rhythm and the intonation of the language they're hearing," Sundara says.

Sundara also studies how babies respond to hearing different languages. In bilingual households, babies switch that rhythm and melody in their babble depending on what language they're responding to. In monolingual households, they don't.

She led an experiment showing that those babble patterns can change, however.

At the beginning of the experiment, each participating baby is 9 or 10 months old and can only babble in what sounds like English. Then, they let the babies spend time with a research assistant who speaks Spanish. "And in these sessions, you are just reading to them, playing with them in Spanish. That's all that's happening."

The babies get about five hours of exposure to the second language spread out over four weeks.

Then, when her team gives the babies another chance to interact with a Spanish speaker, they are able to change their babbling to match the Spanish sounds.

Babies have this special skill for picking up language thanks to something called enhanced neuroplasticity. It basically means their brains are superadaptive.

"When babies are born, they can hear and distinguish all of the sounds and all the languages in the world," says Jeannette Reiff, associate director of clinical issues in speech language pathology with the American Speech Language Hearing Association.

So a baby who hears a couple of languages regularly would be able to tune into both languages. And there are, of course, cognitive and social benefits to being bilingual.

And what about the idea that trying to learn two languages at once would confuse babies. That has since been disproven, Reiff says. But the question still comes up.

"I work with many families and I have this conversation a lot with them," she says. You know, 'We speak three languages in our home. Which language should we choose?' And I say 'All three...We're not confusing [the baby]. We're only increasing brain flexibility and maximizing the neuroplasticity that your baby has right now.'"

That heightened ability to learn language lasts until children are around 5 years old — with some lingering language superpowers lasting until age 12.

So while my baby isn't walking yet and insists on scooting backward on his bottom while blowing raspberries, his babble is one sign his brain is doing amazing things.

As I occasionally struggle to conjugate verbs in Spanish, willing my brain to remember something from high school Spanish class, I sometimes wonder how much easier it would be if I had just started to learn a second language as a baby.