I'm assuming you're talking pulltabs that had a certain TID scale reading, and gold rings that had the exact same TID # readings, right? So that the only "difference" was that one was "scratchy", while the other was "solid", right? I too have heard people say that gold rings "
sound" different, even though they agree that gold and aluminum share the same TID #'s (ie.: all over the lower end of the TID scale). Ie.: gold is "mellower" or "softer" "solid", etc....
But I think that this is only the psychology of "selective memory" though. It's an easy subconscious trick. It works like this: Every time we md'rs stop to dig something, we think "this one sounds different". But when it turns out to be a tab or san slaw or beaver tail, we think "yeah, come to think of it, it DID sound kind of scratchy, etc...". And we immediately forget our premonitions. But after 100 tabs, slaw, and beaver tails, when we finally bring up that gold ring, only THEN do we remember our premonitions, and think "aha! I
KNEW this one sounded different!"
It's the same thing that happens when we think our dreams came true that we dreamt. Each night, we dream hundreds of dreams, none of which come true. When we wake up, we forget them within a few minutes, right? But if one coincidentally comes true (that song you dreamt about is on the radio, or the friend you dreamed about calls and woke you up, etc...), only THEN do we remember the dream, and think "aha! I'm psychic!" But all it is, is selective memory.
Put it this way, I've heard of even one Whites dealer who made this claim about gold sounding mellower or solid or some other sort of supposed way to discern gold from aluminum. I challenged him to go to any inner city blighted junky park, and see how many gold rings he could find, while leaving the junk in the ground. He stopped making these claims after that
(at least not to me. He might still make the claim to poor newbies who thence forth go knock themselves silly in junky turf perpetually thinking they must be doing something wrong). Heck, even at a 50 to 1 ratio most of us would gladly accept, right? But when it goes to 100's to one, then it becomes nothing more than random odds, and no, there is no sound difference.
Yes, some aluminum items sound "scratchy". But other aluminum items lock on quite nicely. Also some gold rings might sound "scratchy". Because you see, every item sounds different than each other. No two gold rings sound alike, no two aluminum wads sound alike, etc.... Sorry to be a kill-joy.
You can do some ring-enhancement exercises by knocking out commonly recurring junk items (like round tabs, smaller foil, etc...), and yes, passing bi-metal-tone sound "scratchy" targets. Lots of ways to lessen the punishment. But you will be passing some gold rings and jewelry, and you will be digging junk. Especially in a turfed area where can slaw and chopped stuff exists, that comes in all over the spectrum.