On Windows, whenever the microphone is in use, the microphone icon should be visible in the system tray and people can learn what is using the mic by going to Microphone in Privacy of Settings. A lot of things can use the microphone on Windows computers: Skype, Viber, etc. That being said, it's not uncommon for the mic to be used by seemingly irrelevant apps/services such as Host Process For Windows Services. In the case that you want to tackle the issue but don't know the best approach, our clip is going to be of use to you.