This is known as "ring enhancement" programming (either via audio, or TID's #s, cross-hair coord's, etc...). You merely take a sampling of the most common gold rings, and merely take a sampling of the most commonly recurring junk items (ie.: round tabs, square tabs, foil wads, etc...) likely to occur in a location. Then you can just do spreadsheet analysis, and come up with the best #'s/sounds to dig.
But it gets thrown out the window VERY quickly, if you are in an area of can slaw, or larger foil wads. And you WILL miss gold jewelry.
So it is not lending a hand at all to the "gold sounds different from aluminum" discussion. It has nothing at all to do with gold vs aluminum that is. It's merely looking at commonly recurring junk items (if you're lucky enough to be in a location where the majority of junk falls in to certain recurring items), verses commonly recurring gold ring TID's.
One thing too, you have to consider, is that rings with a crown on them (ie.: one side heavier than the other) do not lie flat in the ground (turf, etc...). A friend of mine ........ about 25 yrs. ago, staked out an area of an upscale old-town park, where he had pulled lots of silver from over the years. He figured he'd been missing lots of old nickels too, and gold jewelry. So he made it his mission to strip-mine every single signal from a given zone (which had been particularly good to him) to experiment with this. Over the next several months, he'd go a time or two per week, and purposefully dig every single signal from a staked out section of this grass. Every time he went, he carted off an apron full of junk, foil, tabs, teensy grommets, etc... And sure enough, at the end of a few months, he did indeed have a few V nickels, a couple of buffalos, and ........... yes ........ a few gold items. He decided that it JUST wasn't worth the trouble. And his time would have been better spent simply going to the beach, if he was that "hot and bothered" to find gold items
But an interesting phenomenom developed during his experiment: As he took meticulous notes and records of every single item found (so he could do ratios studies and so forth), he would slowly retrive/dig every object, so he could measure its depth, for instance. He noticed an interesting phenomenom when digging gold rings: Every time he dug a ring that had a crown on it, it was never flat. It was always tilted down in favor of the heavier end. In fact, some were actually vertical in the ground! Had he not been doing a slow meticulous study, this detail might not have been noted. His conclusion was that when they're tilted or on end like that, you're certainly not going to get the same TID that you would, if the ring were flat.