Although Grayson Clamp, 3, was born without hearing nerves in his ear, he can now sense sound thanks to an experimental electrical implant that directly stimulates his brain.

Video of Grayson hearing sound for the first time shows his shocked face when he hears his father's voice for the first time. As Grayson's father, Len Clamp, tells him, "Daddy loves you," Grayson drops his toy and whips his head around looking for the source of the sound.

"I've never seen a look like that today," said Clamp, of the day the implant was first turned on. "He looked deep into my eyes. He was hearing my voice for the first time. It was phenomenal."

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This spring Grayson received a brain auditory stem implant at the University of North Carolina Hospitals. He is the first U.S. child to receive the device, which was given to him as part of a U.S. Food and Drug Administration clinical trial.

"We're bringing the potential for hearing to a child who can't hear and had no other options," said Dr. Craig Buchman, head and neck surgeon at the University of North Carolina Hospitals.

To help Grayson hear, Buchman and his team placed the implant directly on the brain stem in the area where sensory impulses are normally received from the ear. Unlike the cochlear implant, which stimulates the audio nerve, the brain auditory stem implant stimulates the brain directly, turning data from the receiver into sound.

ABC News