This question was posted on the ficlist by Genevieve, who asked if anyone on the boards had any further ideas:

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Someone's asked me a trivia question I can't figure out. I wondered if anyone here could help. Does anyone recall if there was an episode that featured a scene where Luthor contacts Clark through a hyper sonic signal, very similar to the scene from SUPERMAN THE MOVIE???

I want to say yes, but I can't remember what episode it was, or even if I'm just remembering something from the comic books. I have this vision of Superman coming to a dead stop in mid-air, and listening to a message. Anybody got a better memory than I do, and remember what episode it might be?
Carol mentioned Jimmy's watch in GGGOH, the messages in Wall of Sound, the bomb under the table in WHALTTA, and the globe messages in Foundling.

That's about all I can think of, but Genevieve is looking for more specifics, I guess. Where not only is a hypersonic message used, but Superman, hearing it, stops in midair to listen.

I don't think NK telepathy counts, but was there a hypersonic message used as part of Ching's testing?

Anyone else have any thoughts?

When in doubt, think about penguins. It probably won't help, but at least it'll be fun.