Ok, so audiograms have the y,-axis inverted to show hearing loss as a downward graph. 0dB refers to the calibrated baseline volume. Each non-zero value states how much volume must be added from baseline to hear the pure tone frequency.

Edit: u/eahle_565 asked a good question. Upvote curiosity, you pessimists bastards! Everyone who hated school or believes they’re not “math people” had a teacher just like you! 🖕