This is a new standardized test for Noise Isolation Class.
This test is different from STC test.
STC is designed for materials and partitions, where NIC is designed for sound isolation enclosures.
Noise Isolation Class (NIC) – A single number noise reduction rating of a partition, room, or enclosure, where sound pressure level differentials are measured in one-third octave bands and compared with standard contours as per ASTM E 413.
Test results noise reduction graph in dB & NIC (SPB / Double wall):
Test results NIC by frequency: (SPB / Double wall):