Yes I did use REW. It took a little tinkering with Microsoft Excel because I don’t believe subtracting the difference between two measurements is a feature built in REW. It’s NOT a straight forward process the way I did it.

Step 1: Use REW to take ground plane (GP) measurements of any sub(sealed is easier for this purpose). Audioholics.com has a good article on this.

Step 2: Use REW to measure the drivers listening position with the same sub in the car.

Step 3: In REW select one measurement, go to File>>Export to convert each measurement to a .csv file so it can be opened in excel. Repeat for the other.

Step 4: All the data points (Frequency, SPL, & phase) are in one column so I had to use the “text to column” wizard in Excel to get the data into separate columns so I could apply formulas.

Step 5: The frequencies used to in the ground plane and car measurements differed very slightly, by thousands, so I input a formula in excel to average them.

Step 6: Input a formula in excel, to subtract the in car SPL from the GP SPL. The difference in these two numbers is your car’s transfer function.

Step 7: Replace the original data with the new data you just created.

Step 8: In REW go to File>>Import Frequency Response and find the new Excel file you created and the transfer function will now show in a graph in REW.

Step 9: Don’t tell people how nerdy you really are. You’re supposed to be cool because you own a Corvette.