Hey everyone, I’ve got a question that’s been bugging me. So, we all know that sound needs a medium to travel through, like air or water. But what happens with sound in a vacuum cleaner? I mean, it’s a vacuum, right? Does it just get all quiet in there? Or is there something I’m missing? Thanks for satisfying my curiosity on this one – I’m really stumped!
It’s not a complete vacuum (hard vacuum) inside the vacuum cleaner, just a lower pressure.
The loudest sound possible in a medium is when the pressure waves alternative between complete vacuum and 2x the pressure of the medium. In standard atmospheric pressure it’s about 194dB. Inside a vacuum cleaner it would be slightly less, but you’ll never achieve sound that loud, so it doesn’t really matter.
TL:DR: No difference in sound levels inside a vacuum cleaner.
Sources: https://physics.stackexchange.com/a/275460