Interactive NC / RC Graph

Enter sound pressure data for the 1st (63 Hz) through 8th (8000 Hz) octave bands. If you do not have data for the 1st and 8th octave band, enter a zero (0). Zeros in the 2nd through 7th octave bands will be used in the NC and RC graphs.

If you have Catalog Sound Power data, you must subtract the AHRI 885-98 attenuation factors from the sound power data to determine the estimated room sound pressure data to graph.

The table below shows the AHRI 995-98 attenuation factors for radiated and discharge sound used in the Titus catalog.

Octave Bands
2 3 4 5 6 7
Radiated Sound 18 19 20 26 31 36
Discharge Sound < 300cfm 25 28 39 53 59 40
Discharge Sound 300 - 700cfm 27 29 40 51 54 39
Discharge Sound > 700cfm 29 31 41 51 52 39

The NC / RC Graph is based on AHRI 885-98.

To calculate room sound pressure from catalog sound power data, enter the catalog radiated or discharge sound power for the 2nd through 7th octave bands and click "Calculate Radiated Room Sound Pressure" or "Calculate Discharge Room Sound Pressure".

For Discharge Room Sound Pressure, the calculator uses the AHRI 885-98 discharge sound attenuation factors for airflow > 700 cfm (shown above). NC values for lower cfm's will vary slightly.