> Is there a simple test to verify that my deep bass panel traps that I built are working properly? <
To test for air leaks, pound gently on the front panel while you pass your hand over all of the seams feeling for air spurting out. There's no easy way to actually test them for absorption. But if you built them correctly - no air leaks and the rigid fiberglass is not touching the front panel - you can play sine Waves and feel that the panel vibrates in sympathy. You might even be able to get a sense of their center frequency by feeling at which frequency the panels seem to vibrate the most.