Here are a few quiet vacuum cleaner web sites.
I haven’t tested any of these vacuums myself except for the Nilfisk Family vac.
Some of these are shop vacs and some are commercial vacs. But the quietest ones seem to also be the most expensive. They are commercial vacuums, meaning they are marketed toward professional cleaners. They are made to work all day long, all year long. I did see the Nilfisk Family vac being used at my town’s technical school. I thought it was quiet so I brought my decibel meter in the next day to test it. The one I tested was 67 decibels at 5 feet. That’s quieter than my Sharp Twin Energy Up right vacuum that tested at 73 decibels at 5 feet. We also have a Craftsman shop vac that's 90 decibels!
These are the two quietest advertised vacuums on the internet that I could find: The Nilfisk GD 2000, and the Numatic NVQ-380 commercial vacuum. They are in the 450 to 550 dollar ranges U.S. The Nilfisk GD 2000 claims 44 decibels and the Numatic NVQ-380 claims 47 decibels.
I wish consumer reports magazine would list the decibel levels of the vacuums it tests. How else are we to tell if their vacuums are quieter or louder than the ones we already have. Maybe we could write an appeal to their engineering department or their president.
I still have to build up the courage to go into a vacuum cleaner store and say, " Can I test the decibel levels of your vacuums because my ears are sensitive to sound". Why do I feel like a teenager trying to buy a package of condoms from the pharmacist at the drug store? Yes, I’ll take some gum, that comb there, condoms, shampoo, tooth paste, and band aids... What... size...? Large?
As far a testing, distance from the vacuum makes a difference in sound levels. I would like to suggest a standard distance of five feet or 150 cm, because that is about the average distance a person’s ear would be from the vacuum while vacuuming. Some decibel meters have two settings, (A) and (C). Always test at setting (A) as it is filtered to hear like the human ear. Setting (C) is instead used for calibrating musical sound systems.
It would be nice if we all could test our vacuums and post them to a list on this website. That alone would bring a lot of people to this website as they search for quiet vacuums. People are also searching for quiet computers. There are lots of websites devoted to quiet computing.
Consumer Reports said the Samsung Quiet Storm vacuum was quiet but this Epinions site reviews say it has hose splitting problems. No decibel rating reports. Consumer Reports claimed that the Sharp Twin Energy was quiet too, but it turned out to be 73 decibels.
Porter Cable link 60 decibels