I agree that the auratus (especially by blues) are more shy than others, but this can be overcome as they mature with lots of simple cover to make them feel safe. By "simple," I mean a rather plain tank set up without retreat holes under or behind moss, etc. where you can lose track of them, but with a lot of foliage and some shallow, covered dishes or huts, so they are always a hop or two away from "safety." I also let condensation build up on the glass, at which time they will actually come out and climb the glass. With time, they will become more bold and brave, though never to the extent of leuks that may hop on your hand in anticipation of food and practically bowl you over, or the galacs that will get next to the glass and stare you down if they think they need a meal. I even named one of my blue auratus "Larry" after Garrison Keelor's radio character who was discovered living in the cellar after he had disappeared 15 years before.
Although my auratus are apparently breeding now, because I've found eggs, I have never identified any calls that come directly from their tank. Unlike the imitators, they don't seem to be boistrous or quite as oblivious about "doing it" in public. I can tell the calls of the imitators and leuks, (of course if you miss leuks, you are deaf), but the auratus calls must blend in with other sounds to my ears. Even my boys, who have sharper hearing, can't swear they have ever heard them for sure. Maybe they just whisper sweet nothings. Placido Domingo, they ain't.
To get this photo, I scattered in some fruit flies just before I uncovered the blue dish they were all huddled together in. That's Larry, still in the dish.

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Patty
Lost River, Idaho
4 D. auratus blue
3 D. galactonotus pumpkin orange splash back
5 D. imitator
4 D. leukomelas
4 D. pumilio Bastimentos