[Lerc]

This seems to be targeted at signals that are already quite close. Is there anything similar for broad ballpark similarity?

Whenever I save searched for such things I have more often encountered techniques designed to detect re-use for copyright reasons.

I have played around with generating instrument sounds from a blend of very few basic waveforms with attack,decay,sustain,release, pitch sliding and bell modulation.

While it is quite fun just trying to make things by tweaking parameters, your ear/perception drifts as you hear the same thing over and over.

It would be really nice to have an automated "how close is this abomination?". I'd even give evolution a go to try and make some more difficult matches.

[tux3]

How close is broad ballpark, have you tried chromaprint?

It's probably far from state of the art today, but you can get a percentage similarity out of it. I've successfully used it to find similar (or outright duplicate) songs in a big library

[Lerc]

Things like chromaprint are why I have found it difficult to search for what I want.

These tools are geared towards identifying matches (one to many) Chromaprint specifically bins things into notes assuming it it trying to match music.

I'm after something that will tell me, in human perception, how much a dogs bark sounds like a quack.

One to one comparison of short-ish samples with no assumption of content style.