Could be a bug.

[ホトトギスくん]

After applying v0.6b, I get game over in response to game sounds.
I am not making any sound.
It might be just my environment.
There was no problem with the version at the time of release.

[EXODIAC STUDIOS]

You should check your mic sensitivity in settings. Might be your mic catching your headphone audio.

[ホトトギスくん]

If the microphone calibration is above 50%, I get a "scream" condition even though I am not speaking.
If I set it to 15% or less, it is fine, but it is obviously not right.
Please refer to the screenshots as well.

[ホトトギスくん]

I watched a video on Youtube and this seems to be the norm.
As a developer, how much mic calibration do you expect to play with?