I don't really have any suggestions, but I'm curious if you're running with
an onboard mic on a laptop, or an external mic. If so, is it through the
mic-in jack or a usb microphone? I have a similar problem with the built-in
mic on my laptop, but sound levels are normal if I use the 3.5 mm mic jack.

I use a headset plugged into the audio ports on the motherboard, at the back of
the computer. The hardware works fine in Windows. Oh, I just remembered: it
works fine in Skype under Mint, just not in Audacity or Sound Recorder.

You might want to install ALSA mixer and change the input settings.

I have alsamixer installed. What change would you suggest?

Change your input settings. Check to see if it on line in or mic.

Are you running Mint or Ubuntu? You mention both and it is confusing. If
you have both installed which one can't you record audio in?

I use Mint 64-bit with gnome. Under the hood it's Ubuntu, so I
think of myself as an Ubuntu user.