Audiologist Julie Hill said hearing aids are not "valuables" they are essential tools that people need to hear.
"It's your ears," she told the Herald. "You don't check your ears in with the nurse when you come into hospital.
"In hospital, you need them to hear the nurse and to hear the doctor telling you your diagnosis and to participate in your health care."
Readers also expressed their concerns with the comment on Facebook.
Rebecca Slight said: "It's a hearing aid! Kind of essential!"
Gail Olliver said: "Valuables should be left at home? What a crock. She needs the bloody thing to hear."
Mrs King's son, Richard, said the aid went missing the night before his mother was discharged.
A woman had intently questioned the family about the device, rousing their suspicions that it may have been stolen.
Mr King - who gave up a job in Wellington to look after his mother full-time in Auckland - said knowing someone might have tricked them in such a way was heartbreaking - especially for their mother.
"These are her last days, when she's remembering and talking about things with us - sharing memories.
"But now it's hard for us to communicate because she can't hear and it's a shouting match and she gets agitated."
Police said investigators were waiting for CCTV footage to be provided by Middlemore.
Mr Pearson said the hospital was "very sympathetic to Mrs King's loss" and an investigation had "concluded the hearing aid had been misplaced rather than stolen".
A hospital spokesperson did not wish to clarify or add to Mr Pearson's comments.
Since today's Herald article, the family had also been inundated with offers from generous readers to provide a new hearing aid.
