Watch deaf toddler Grayson, 3, hear his dad for the first time

The moment 3-year-old Grayson Clamp hears his dad speaking for the first time, his eyes light up in shock.

Grayson was born deaf, but thanks to new technology, he became the first American child to receive an auditory brain stem implant three weeks ago at a University of North Carolina hospital in Chapel Hill, N.C.

The medical centre said the toddler was born without hearing nerves and cochlear implants couldn't help him. But after surgery, Grayson's silent world changed forever when he heard his first sounds.

In a video describing the procedure, neurosurgeon Matthew Ewend said a small electrode sends sound through a cable from the brain, through the bone and finally, to a receiver that lets Grayson hear. A warning: the video shows some graphic images of surgery.

Grayson's surgery was part of an FDA trial that could help other deaf children hear, if the new type of implant is approved.

Another toddler, 2-year-old Cooper, had a similar reaction to Grayson's when doctors activated his cochlear implant in 2011, according to a video uploaded to YouTube. The user who uploaded the video commented recently that Cooper is now 4 years old and he's slowly learning to speak.

Sarah Churman was 29 when she heard her own voice for the first time. A week after she received her first implant from Envoy Medical, which cost her family $30,000, Ellen DeGeneres told her on live television the company was reimbursing the cost of her surgery and providing the second implant free.