Installing an additional layer of acoustic drywall over an acoustic membrane between materials and closing all gaps with an acoustic sealant to block cracks and gaps in both new and existing walls is the most efficient noise reduction method but using resilient channels, applying blown-in insulation, or covering the entire wall with soundproof blankets and curtains are other common solutions known to reduce noise. 
Whether you?re trying to get some shut-eye or working from home, a constant babble of noises from next door can become a source of frustration and affect your mental well-being. In such situations, the only sensible option is to soundproof existing interior walls through which the sound is heard.  
My guide shares some of the best soundproofing methods by which you can do so!
Learn How to Soundproof Existing Wall

Soundproofing Elements To Keep In Mind
To ensure your soundproofing methods work properly, you must know what factors affect their effectiveness. While most materials function independently, they can be used together to deliver the best results when you soundproof existing walls.  
1. Blocking Or Reduction
Sound waves function by creating vibrations in objects, which may be solid, liquid, or gas. But how easily they can travel through various objects depends upon the mass. A larger and heavier object will have more mass and it will be more difficult for sound waves to travel through it.
Thus, a solid surface that is dense enough can reduce sound w...