audacity on Big Sur

I tried repeatedly to record using Big Sur 11.4 with both versions of Audacity. It would not recognize sound input. I tried with Catalina 10.15.7 and it works

Is this on different machines? Have you checked that Audacity has permission to access the microphone?
– Bill

Which versions? (There have been well over 50 versions released since May 2000)
Look in “Audacity menu > About Audacity” for the exact version number.
The current version is Audacity 3.0.2 and it is available from the Audacity website: Audacity ® | Downloads

You may need to give Audacity permission to use the microphone (Apple uses the term “microphone” to refer to any audio input)
See: FAQ:Recording - Troubleshooting - Audacity Manual

hi, I recently downloaded Audacity 3.0.2 on my MacBook Air Big Sur, & I realised it takes forever to apply effects like noise reduction, or generate silence (for just a tiny section of recorded audio), can someone please guide me on what’s the issue?

We don’t know yet. This is a problem affecting a few Audacity users, but most of us can’t reproduce the problem, which is making it very difficult to find the cause. We are investigating.

The next version of Audacity (3.0.3) contains some fixes for irregularities that we’ve found, but we won’t know if these will fix the slowdown issue until it has been released and used by lots of people. I’m hoping that there will be a “release candidate” available for testing before Audacity 3.0.3 is released.