macOS Big Sur 11.5
I am not very good at using Audacity but it has worked well in the past. When I tried to use it for the first time on Big Sur, I see a strong squeaking noise. I have attached a screen shot for your reference. Thanks so much for your help! I am not very good with tech so I apologize if the solutions look obvious to you pros.
I’d guess it’s feedback. Feedback is the squeal you get when the output from the speaker feeds-back into the microphone in a continuous loop and it gets re-amplified over-and-over quickly goes to the maximum.
It can also happen internally if you are recording streaming audio (other output from your soundcard) while monitoring what you’re recording (i.e. with Software Playthrough turned-on).
Since there are buffers that introduce a delay, any feedback through the computer might start with an echo before it gets louder-and-louder and out-of-control.