Two interior walls: why decoupling beats insulation alone
Standard 2x4 wall + batts ≈ STC 36-39
stud
studs short-circuit sound: vibration
conducts drywall-to-drywall
Same batts + resilient channel + 5/8 in. ≈ STC 50+
resilient channel
channel breaks the vibration path;
insulation absorbs cavity resonance