I am running Audacity 2.3.3 with Mac High Sierra 10.13.6. Occasionally in one of my audio files, I hear this click – I am not clicking a mouse or doing anything else that I can think of that would cause it. I have a Samson G-Track Pro and a pair of headphones connected into it. I’ve attached a sample of what I’m talking about. You’ll hear it right around “positive connotation”.