Select one track or file > Analyze > Contrast > Measure Selection.
Write that down.
Measure the other one.
Contrast will give you the RMS or overall loudness of the performance. That’s not the final word because that doesn’t take into account tonal differences, but that’s the way audiobooks measure general loudness.
You can also open both performances and select one at a time and measure Forground and Background.
Koz
so that I know the mic actually works?
I’m a little foggy on what you actually did. It should be possible for you to switch between two microphones. Are you recording a good microphone and then both? You can sort what you’re recording by scratching the microphones.
https://www.kozco.com/tech/audacity/clips/ScratchTest2.mp3
You can also click on the recording sound meter > Start Monitoring and it will wake up and bounce without making an actual recording.
Some of these tools come and go with the Audacity version. You should be using Audacity 2.4.2. Help > About.
Koz
When I did it, I wired my test microphone into a male XLR connector and then plugged it into a small sound mixer. Compare with an actual manufactured microphone.
You can get “tonal analysis” by crunching up a newspaper in front of the microphone.
That’s a remarkably good “white noise” test. Analyze > Plot Spectrum. Audible tones go from 20Hz to 20,000 Hz. Low tones on the left, loud is up.
Try as much as possible to crunch the same way each time and use the same newspaper or section of the newspaper. Don’t overload anything and use WAV files instead of MP3. MP3 makes sound distortion.
Koz
You have all the problems that performance actors do. Don’t do the test in a “live” or echoey room. You’ll be analyzing your room in addition to the microphone. I had access to a small movie theater (screening room) with very few echoes and almost no noise.
Koz
Fair warning if you’re using the Mic-In or Headset connection on your laptop, that has 5 volts DC on the connection because “computer microphones” need that. That can mess up a home microphone design that doesn’t need it.
Koz
Ideally you would use an audio interface that has two identical microphone inputs so that you can record one mic on the left channel of a stereo track, and the other mic on the right channel. You could then use a variety of tools that are available in Audacity to compare the two channels (for example: “Plot Spectrum”: https://manual.audacityteam.org/man/plot_spectrum.html)