I have never had an air purifier so wasn't sure what to expect. It sounds like a quiet fan so not bothersome. This one has a guide on the side to see what is normal and when the air is in a good range the light indicator is blue and turns red when it's not good which is under 70.  It does have a filter that needs to be cleaned when it gets dirty. There is a warning/indicator for that as well.  It's super easy to use just plug and play. My air quality is all over the place. Last night blue, this morning red.