j_garcia Audioholic Jedi Apr 29, 2026 #3 In what context? Your room? I would expect it to remain constant even as SPL increased. This article does not mention what dB it is taken at, in a cursory read. NRC Rating: Understanding the Noise Reduction Coefficient | ASI Understanding what an NRC rating is and how it works will help you find the best acoustical product solutions you’ll need. Learn more here! www.acousticalsurfaces.com Just noticed that it says that the NRC rating is being phased out. "The NRC rating is currently being phased out but is still a required calculation so current ASTM C423 tests can be compared to older ones. Its replacement is the Sound Absorption Average (SAA), which takes the average Absorption Coefficient over a greater range of frequencies, and with more frequencies in-between; 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, and 2500 Hz." Last edited: Apr 29, 2026
In what context? Your room? I would expect it to remain constant even as SPL increased. This article does not mention what dB it is taken at, in a cursory read. NRC Rating: Understanding the Noise Reduction Coefficient | ASI Understanding what an NRC rating is and how it works will help you find the best acoustical product solutions you’ll need. Learn more here! www.acousticalsurfaces.com Just noticed that it says that the NRC rating is being phased out. "The NRC rating is currently being phased out but is still a required calculation so current ASTM C423 tests can be compared to older ones. Its replacement is the Sound Absorption Average (SAA), which takes the average Absorption Coefficient over a greater range of frequencies, and with more frequencies in-between; 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, and 2500 Hz."
H highfigh Seriously, I have no life. Apr 29, 2026 #4 ifsixwasnin9 said: ie. As dB increases does NRC rating decrease? Click to expand... Specifically, what materials are you considering?
ifsixwasnin9 said: ie. As dB increases does NRC rating decrease? Click to expand... Specifically, what materials are you considering?
TLS Guy Audioholic Jedi Apr 29, 2026 #5 ifsixwasnin9 said: ie. As dB increases does NRC rating decrease? Click to expand... No
H highfigh Seriously, I have no life. Apr 29, 2026 #6 TLS Guy said: No Click to expand... Depends on the material and its mass and the SPL. If the SPL is hgh enough, it can partially compress some materials and that will reduce the NRC. I don't think the OP is dealing with extremes, but that's the reason I asked about which material they were asking about. IMO, averaging the NRC is going to cause problems if the frequencies aren't stated separately and specific ranges need to be addressed. I also think materials will be mis-used and wrongly recommended, based on this average and confusion when trying to relate the old & new specs.
TLS Guy said: No Click to expand... Depends on the material and its mass and the SPL. If the SPL is hgh enough, it can partially compress some materials and that will reduce the NRC. I don't think the OP is dealing with extremes, but that's the reason I asked about which material they were asking about. IMO, averaging the NRC is going to cause problems if the frequencies aren't stated separately and specific ranges need to be addressed. I also think materials will be mis-used and wrongly recommended, based on this average and confusion when trying to relate the old & new specs.
