I have the voice chat options disabled but SC2 still interacts with my headset’s microphone.
My headset is a Senheiser BTNC 4.5 which has noise cancelling and it struggles as acting as both a computer headset and microphone. While this is not related to you specifically I don’t have an issue if I set my Windows sound to use the headset and use a different microphone however every time I launch SC2 I have no sound because SC2 uses the mic from my headset even though i unchecked voice chat.
This is corrected as soon as I click on the voice chat menu. It detects my settings without me changing anything an I regain volume in my headset.
The issue here is that SC2 seems to be interacting with my headset’s microphone at launch without checking my voice chat settings. This is not an issue in other blizzard games where the windows microphone settings are respected.