Not-great mic, but not abysmal. Is it salvageable?

I’ve spent hours going through every tutorial I can find, trying to touch up these recordings, but I’m brand new to audio processing and I honestly have no idea what I’m doing. I can’t tell if the recordings are a lost cause, or if I’ve missed something important. Here’s a sample:

Is there anything that can be done?

Thank you in advance for the help!

You can’t magically transform that into good quality sound.

You can make it sound less muffled by applying the “Bass and Treble” effect with -12 db Bass and +12 dB Treble.

This isn’t touching up. That’s a badly damaged sound clip. You are in disaster recovery. It’s wool-blanket muffled, but it also has rumble and thumping sound over the voice and sizzling essing.

How did you make that? In detail.

Is it a surveillance recording? Was the recorder in your pocket? I can account for the muffling, but the sizzling essing is new.

Did you try to recover audio from analyzing video pictures? That’s a relatively new technique where you analyze the vibration of paper or other flat object in the video frame.

I know you think you’re recording from your microphone, but you may not be. It’s not that unusual for a computer to switch to the internal microphone and not tell anybody. Of course, that’s never happened to me [ahem.]