Soundproofing of apartments?

[Joshua Mast]

I have a duplex that is divided up by floors: apartment 1 is on floor one and apartment 2 is on floor two. I have an issue with sound travel between the two floors. I got one of those dreaded 10:30pm tenant calls last night with complaints on the sound. I have had this property for 7 years, and, in general, the issues don’t present themselves if the tenants are going to bed around the same time. The bottom tenant is original and doesn’t complain much; until this last tenant moved in. She tends to goto bed around 9:30-10:00, but the tenant above her has put their office in the room above the 1st floor bedroom and will work sometimes until 2am. No issues except she will use a rolling chair, may drop things, may play music, etc. as much as I try, they just can’t seem to get along. I am curious about different methods to address this issue - soundproofing/dampening, ask them to move their office to a different room, get new tenants, etc. I had looked into having insulation blown into the ceiling but am not sure if it will be very effective. Any help is appreciated! Josh