The music, PA system and half of the store lights are switched off, fidget toys are given to children and staff are asked to not work with stock or rattle around trolleys and cages.
The quiet hour got positive feedback in Marton, so previous store manager Kirsten Dinnan wanted to bring it to Whanganui.
"The conservative statistics show that around 2000 people in Whanganui have sensory processing issues, that's around 800 families," she said.
The first quiet hour was on May 1 and will continue every Wednesday around mid afternoon to align with school pick-ups and daily routines.
Dinnan, now the store manager of Countdown Trafalgar Square, said the staff and elderly found it really enjoyable.
"We had an elderly lady waiting outside for the hour to begin as she found it much more enjoyable to shop in."
Hogg said many people benefited from the hour.
"People with Alzheimer's, a head injury, epilepsy, chronic fatigue syndrome, the list goes on," he said.
"So many times people are isolated and marginalised. Yeah, online shopping is great so they don't have to go into store but it also makes it so they can't learn social skills."
Learning from his own experience with his son Hunter, he said a quiet hour could have health benefits and help those who have processing issues to cope better and control it.
"It can help parents to teach their kids with sensory processing issues about different foods and basic manners because they are in a calm environment, it's very rewarding to see."
Whanganui Countdown is the fourth Countdown in New Zealand to adopt the hour, with several others considering it.
