'Hello, it's mummy' - watch the adorable moment a deaf baby first hears his mum's voice

A deaf baby boy in the UK broke into smiles when he heard his mother's voice for the first time after being fitted with new hearing aids, and video of the moment has gone viral.

Five-month-old Alex Denman-Sang was born with Bilateral Moderate Sensorineural hearing loss which means he has been practically deaf his whole life, The Sun reported.

He was fitted with new hearing aids at Alder Hey Children's Hospital in Liverpool.

In a clip of the moment, Alex's mother Jen gets his attention by saying his name, and he smiles.

Alex is being held by his dad, and smiles more when she says, "It's mummy, mummy. Hi"

And again when she wipes his face and asks, "Are you slobbering on daddy?"

A clip of the moment went viral after the hospital tweeted Alex's adorable reaction.

It is been viewed more than 800,000 times and has even been shared by comedian Dawn French.