The only time it will get louder is when it detects the air is bad and it will turn itself up to clean out the impurities and then go back automatically in the quiet mode; but even that noise is not bad
If your not looking to spend $1000 + on an IQ Air or Blue Air then consider this model
Additionally, since I have been using the Coway, the air in my home actually feels crisp and smells so very clean
Have noticed improvement in seasonal allergy symptoms
I found this to be a superior product based on past experience with various brands
I may get another one for my bedroom, but right now it doesn't seem necessary