This is the heartbreaking moment a baby heard her father's voice clearly for the very first time - and got the fright of her life.
Little Nellie Rosales was born with microtia and atresia, which means she was completely deaf in one ear and could only hear quieter sounds - but struggled to hear voices.
So when she was fitted with a 'bone anchored hearing solution' and heard her dad Jacob's voice clearly for the first time, she got the fright of her life.
The video shows Nellie, who is now 11-months-old, being fitted with the hearing aid and bursting into tears as soon as she hears her dad's voice.
The device doctors fitted her transmits sound using vibrations from patients' skulls, allowing the ear canal to be bypassed.
Dad Jacob Rosales, 28, said : "It was hard before the hearing aid. Every time I talked to her she would look away so she could hear me right."
"Seeing her hear me for the first time took my breath away. It brought sunshine to my heart, even if she was overwhelmed.
According to Jacob, the difference is night and day and Nellie grew to love her device in a few days.
He said: "Now that she's older we make putting it on something fun. The difference is clear. She can hear things from other rooms and she understands what we say too.
"She can hear dogs outside the house and has stopped turning her head.
"She's at the age where she lets us know what she wants and she gets very excited to put it on."
The microtia and atresia had a large impact on Nellie's life before the device was fitted.
Jacob, from Fayetteville, North Carolina, USA, explained: "We noticed as soon as she was born, on her microtia side she has a little peanut ear.
"They did hearing tests at the hospital and she had no reaction at all on that side."
Jacob and his wife, Sharon Hernandez, 27, are both members of the United States military and are grateful for the health insurance they receive which allowed them to get the device.
Jacob said: "I want to thank the military. The insurance we have is great and the device costs six thousand dollars.
"If we didn't have the insurance we would have had to take out a huge loan for the device, it would have been really tough to do without that insurance."
* Microtia causes one or both of a patient's ears to be underdeveloped and atresia is an underdeveloped ear canal.