Ask HN: Categorizing similar low-frequency audio events?

I have a project that I'm trying to gauge feasibility on. I need to discern between very similar sounds that are all around the same frequency range (40hz-250hz).

Currently I'm using a pair of wired Apple earphones and to record the sounds, and visually inspecting a waterfall spectrogram to find differences.

Perhaps obviously, I'm not having much luck visually analysing it. I don't want learn the ins and outs of machine learning and signal analysis only to find that there isn't enough variability in the sounds.

Is there any simple way I can determine if these sounds can be meaningfully categorised?