that they need to be part of the "choir" in order to hit the right deep notes.

Jordan has made mention of the Ogier's deep rumble too many times for this not to be part of the equation. I also think the "longing" is a device of the Shadow's to seperate the Ogier from human's everyday society enough so that the song has very little chance of re-discovery since these two races have such limited contact.

On a seperate note it seems odd to me why no cities have been created in or near a stedding. The sense of peace and tranquility inherit to a stedding seems attractive to me. Why wouldn't a select group of "hippy" like humans not seek this out and make a stedding home. Especially a non-occupied, Ogier free stedding.

Far Madding is a great example of how many non-channalers would prefer the control of a one power free zone, and the steddings seem like a great option. (that should probably be a post on its own. or maybe already has in the past.)