What is the audible level for digital audio dB units?

I was looking at a soundwave from an mp3 file. I am using the "Sonic Visualizer" app available on Linux. The amplitude is between ~ -0.1,0.1 in my file. I have already learned the amplitude is on [-1,1].

The soundwave is between ~ -40,-10 when I convert the soundwave to a dB y-scale. I have that [dB conversion formula.](https://en.wikipedia.org/wiki/Decibel)

I read online that the [human ear starts to hear near -10dB](https://en.wikipedia.org/wiki/Absolute_threshold_of_hearing).

What does that 0-ish threshold correspond to in digital audio? Why are the dB reported in these audibility studies different from the dB I'm seeing everywhere in spectograms etc?

[![Soundwave in dB and regular amplitude from mp3][1]][1]


  [1]: https://i.sstatic.net/c2VL4.jpg