Grayson Clamp's face lit up in astonishment as he first heard his dad's voice. Grayson is a 3-year-old boy who was born deaf but given the chance to hear by a breakthrough surgery that implanted a chip on his brainstem.

Grayson was born without a cochlear nerve that passes the sound waves to the brain so they can be interpreted and understood. His parents opted for a cochlear implant before but it did not work for the medically challenged kid who was adopted by Len and Nicole Clamp from a foster home.

The Clamps learned about trial studies for brainstem implants for children in North Carolina. The family approached the doctors at the University of North Carolina Hospitals in Chapel Hill in May and had a microchip implanted in Grayson's brainstem so he can recognize sounds.

From the moment the toddler was given a speech processor that sends the sound to the brainstem implant, Grayson can hear.

"Daddy loves you," uttered by Len Clamp were the first words heard by Grayson and the first words that totally changed his life. He is the first child in the United States to receive the auditory brainstem implant.

"He's sound aware, but we don't know what exactly he hears. We're relying on the plasticity of brain to start to sort this out," explained Dr. Craig Buchman, the surgeon who implanted the microchip on the child's brainstem, in an interview with CNN.

According to Buchman, the surgery comes with risks too such as bruising when attaching the auditory implant onto the brain. The implant works by receiving the sound from the speech processor then a small amount of electricity stimulates the cochlear nucleus via the electrodes attached to the brainstem.

"It's been phenomenal for us," exclaimed Len Clamp in an interview with Daily Mail.

The auditory brainstem implant has been approved for adults but it was only last May when the Food and Drug Administration gave the green light to try the procedure for children.

Grayson is only one of only 10 children who were lucky enough to receive the treatment at its early stage. Five of the children were born without cochlear nerve while others suffered from traumatic damage.

For now, no one knows what Grayson hears but his expression when he heard his dad speak is a sign of an amazing medical miracle that will give the kid's life some melody.

See that amazing moment when Grayson first heard his dad in the video below: