Technical

Sound reverberation boards are set in to 5 classes with 'A' being the best performace and 'E' being the lowest.

In the simplest possible terms, a NRC (or Noise Reduction Coefficient) is the number which rates the effectiveness of a material at absorbing sound. 

What Does A Noise Reduction Coefficient Mean?

NRC  Ratings  can  range  from  0 indicating  a  perfectly  reflective  material  to  1 indicating a perfectly absorptive material. 

 

One way to look at NRC ratings is to see them as a percentage of sound that comes in contact  with  a sound  absorption  material and  are  not  reflected  back  into  the room.

 

For example, a Noise Reduction Coefficient of 0.7 would indicate that 70% of sound waves are absorbed by the material.

Technical

In the simplest possible terms, a NRC (or Noise Reduction Coefficient) is the number which rates the effectiveness of a material at absorbing sound. 

 

What Does A Noise Reduction Coefficient Mean? 

 

NRC  Ratings  can  range  from  0 indicating  a  perfectly  reflective  material  to  1 indicating a perfectly absorptive material. 

 

One way to look at NRC ratings is to see them as a percentage of sound that comes in contact  with  a  sound  absorption  material and  are  not  reflected  back  into  the room.

 

For example, a Noise Reduction Coefficient of 0.7 would indicate that 70% of sound waves are absorbed by the material. 

 

How is NRC Calculated?

 

The  Noise  Reduction  Coefficient  is calculated  by  averaging  how  absorptive a material is at four different frequencies: 250hz, 500hz, 1000hz, and 2000hz. 

 

Because  the  “official”  NRC  is  an average,  two  materials  with  the exact same  NRC can  perform  differently  in different  applications. Each  may  work best  at  a  different frequency. 

 

NRC  ratings  are  often  confused  with STC  ratings,  which  are  also  commonly referenced in the acoustic treatment industry.  

 

The key difference between NRC and STC is that NRC is used to rate materials that ABSORB sound, while STC is used to rate materials that BLOCK sound.