Carson Rubin is a kindergartner who likes music and books about snakes.

He whispers and laughs with friends, and can explain the difference between a dinosaur and a crocodile. It's a dramatic improvement from Carson's life of a few months ago.

Related: Child who needs corrective hearing surgery gets wish.

In March 2013, Carson, then 5, was consistently behind his preschool classmates in suburban Atlanta because of a hearing impairment called auditory neuropathy, an interruption of the way the auditory nerve functions.

ABC News

"I think he wears himself out trying to keep up with everybody else," said his mother, Shay Rubin.

His parents said they worried that the condition would not only damage his intellectual development but also endanger his safety.

And although the condition could be cured with cochlear implants, according to his doctors, the surgery was not covered by his family's insurance company, Coventry Health Care, and his parents could not afford the $250,000 price tag.

Related: Parents raising $250,000 to repair child's hearing.

Coventry Health Care denied ABC News' repeated requests for an on-camera interview, but ultimately changed its position on covering cochlear implants for children.

"I kind of couldn't breathe for a while," Rubin said when she heard the news.

One month later, Carson had the first of his corrective hearing surgeries.

These days, Carson's speech has not yet caught up to his hearing, but he has no difficulty keeping up with his classmates and family or making his opinions known.

His mother, who previously had worried about Carson's future, is happy with the progress he has made.

"I think he can do anything he wants to do and be anything he wants to be," she said.