How to average the dB SPL of a measurement over a specific freq range

[jaspertech]

Hello all! I am attempting to use REW to measure how effective various noise canceling headphones are at reducing background noise.

Here's what I am working with
- MiniDSP EARS Calibrated USB headphone test fixture
- A variety of active noise canceling headphones
- A few test tones/sounds
- Kali IN-UNF studio monitors

Here's my process
- Play the tones over the Kali IN-UNF studio monitors
- First, use the the MiniDSP EARS and the RTA feature with no ANC headphones to get a baseline measurement of each tone playing (at a fixed volume)
- Then put a pair of active noise canceling headphones on the EARS and use RTA to get additional measurements of each tone playing

Now with the baseline vs ANC headphone measurements I can compare the graphs to see the reduction at various frequencies.

My question is: is it possible to calculate the average reduction between the no headphones measurement and a specific headphone measurement over a set frequency range (thinking 20hz to 1000hz since that is where ANC can really help)?

Any thoughts, comments, suggestions would be very appreciated. I am new to REW, so doing my best to figure this out!