After going through the website's rigorous camera tests—and performing impressively—the OnePlus 8 Pro has now also been subjected to DxOMark's audio tests. It is, at the very least, competitive, as it compares nicely to other flagships like the S20+ and Pixel 4.
https://www.notebookcheck.net/DxOMark-The-OnePlus-8-Pro-offers-audio-performance-on-par-with-the-Galaxy-S20-and-Pixel-4.469556.0.html