It's nasty audio truncation/distortion when played back in 3D space. (Reason why the 1911 chirps). Recommend posting an issue to github about it. I don't think audio is a high development priority at the moment though.
Gigabyte P67A-UD4-B3, Intel Core i7 2600K (passmark 8555), 16GB Corsair DDR3, EVGA GTX 970 SC (passmark 8637), Win10 Pro 64-bit, Primary monitor @ 1920x1080, secondary monitor @ 1280x1024