I have most of the HUD helpers turned off. I have noticed when flagrantly spotted, there is a sound cue that indicates such. Are there specific sound cues for detection level as there are HUD cues?

Also, if there are soldiers walking around saying "I"ll find you!" does that mean Corvo was absolutely spotted? I ask because in Overseer mission, I've knocked out both Curnow and Campbell and carried them away with no guards present. But everytime I do, guards start walking around as described above. I am certain I have not been spotted, since there are no guards present, but they are acting as if I was.