As the others said, seal up any access point with steel wool or wire mesh.  

@Todd Bailey, I have been doing some research about soundproofing because am currently house hacking 4plex two units upstairs what I am planning on doing is removing the cell, adding R13 Thermafiber Fire and Sound Guard Mineral Wool Insulation Batt and resilient Channel with resilient clips to decouple the ceiling and one layer of 5/8 🤷🏽

I have had for 17 years now- what was originally Cotton States - but merged with Country Insurance.

jack cotton suggest calling the property appraiser and paying for it.  

Your statements suggested the only reason for what he had explained was because he was doing something wrong or because he was incompetent.I am sure there are rare stories of whites growing up bruising their knuckles picking cotton in a forced labor environment.

Flying the airplanes when I travel Surgery on myself Filling my own cavities Cutting my own hair Making my own clothes Picking the cotton for those clothes (Ah, no you do not want to go there.)

Pull out all the stones and stuff steal wool in the gas lines coming up from the basement.

@Amy Arata Here is a link to Rock Wool's DIY video outlining a good soundproofing system.

Cotton towels.

@Keith LewisIf the upper floor is a separate unit, then the space between it and the ceiling of the lower unit, if properly fire rated will be filled with a non-combustable "insulation" such as rock wool which also provides significant sound deadening.