Noise Issues from Tenants

[Vanessa S.]

I own a downstairs condo which I rent out. The upstairs neighbor complained of hearing loud noise from the TV very late at night from my tenants back in 2016. I informed my tenants of this and they were very compliant to turning their volume down when watching tv late at night. I received another complaint about this from the upstairs neighbor again yesterday. They are now complaining of the loud volume that occurs during the day as well as late evening, enough to disrupt their sleep. They attempted to knock on the door of my tenants when this occurred but the tenants did not answer the door. I have never had an issue with this with previous tenants nor when I lived there. I have had the same upstairs neighbors the entire time. Any thoughts as to how to proceed? My property is in a highly desirable area so finding new tenants would not be an issue. Any input is greatly appreciated. This is my first time dealing with this issue.