Autistic boy breaks his silence, prompted by the rumblings of a garbage truck

Greyson speaks, delighted by a garbage truck 2:17

Thursday on "Nightly News," we heard from mom-of-two Chrissy Kelly, who writes a blog about "life with my two adorable boys on the autism spectrum." Her son Greyson, like many children with autism, has struggled to communicate. But remarkably, it was the sound of a garbage truck that helped break into his world. 

Read Chrissy's blog, "Life with Greyson + Parker"