When sourcing sound isolation panels, the most critical metric is the NRC (Noise Reduction Coefficient), which should ideally be 0.85 or higher for high-performance acoustic treatment. Additionally, check the STC (Sound Transmission Class) rating if your goal is to block sound from traveling between rooms; a rating of STC 50+ is standard for professional environments. Material density is also vital—high-density polyester fiber (150-230kg/m³) or mineral wool offers superior absorption compared to low-grade foam.