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.