The current TestGenerator is virtually unusable for producing consistent white noise. White, pink, and brownian noise produce extraneous audio and pitched artifacts detracting from the broad bandwidth noise. Brownian noise can also produce random clicks or pops.
A key tell here is to record and then loop a 5-10 seconds of each noise type. Within a few short passes, you should be able to reliably pick out the artifacts as within a loop they will create an audible rhythmic pattern.
After extensive listening test, I can confirm these unwanted pitched artifacts are not present in other online generators, and have migrated this portion of my project over to Logic Pro X, where it’s “Signal Generator” plug-in works as expected.