Join the news democracyWhere your votes decide the Top 100
But after having hearing aids fitted by doctors, Lachlan can hear the voices of his parents, Michelle and Toby, for the very first time. His reaction is priceless.
The video was first posted on Facebook in November 2012, but gained further recognition after being uploaded to YouTube by Toby this week.
Now two years old, Lachlan has been working with therapists at Taralye, an oral language centre for deaf children in Blackburn, Australia.
His mother, Michelle, hopes the video will help to reassure other parents whose children face a similar procedure.
"I hope it can give some other families the realisation everything is going to be okay," she told Daily Mail Australia.
More: Today's life lesson is brought to you by Grover the pug