NRC Rating

**Strutt|Criteria|Ratings|Absorption|NRC** calculates the Noise Reduction Coefficient (NRC) of the current row of the worksheet.

In a 1/3 octave band sheet, the NRC rating is calculated as follows (in accordance with ASTM C634):

`NRC=(alpha_(250)+alpha_(500)+alpha_(1k)+alpha_(2k))/4`, rounded to the nearest 0.05

where:

`alpha_(x)` is the absorption coefficient in each **1/3 octave** band.

In an octave band sheet, NRC is calculated as follows (this is NOT in accordance with ASTM C634 and is provided for reference only):

`NRC=(alpha_(250)+alpha_(500)+alpha_(1k)+alpha_(2k))/4`, rounded to the nearest 0.05

where:

`alpha_(x)` is the absorption coefficient in each **1-octave** band.

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