The least expensive option is going to be to create white noise.
Otherwise, you'll need some type of sound insulation and dense pack cellulose might be able to be retrofitted into the wall cavity. But ... read more
Oftentimes the attic is the place to start. Make sure you have plenty of ventilation, both intake and exhaust. Check the soffit cavity to make sure you it isn't clogged with insulation. There are f ... read more