Any noise produced by SCP-513 immediately induces strong anxiety in all sentient beings who hear it, regardless of their previous mental status. Victims report feelings of being watched by an unseen entity and present elevated heart rates and blood pressure. Roughly one hour after exposure, victims begin to catch glimpses of SCP-513-1 when performing any actions that result in a sudden change in visual perception. SCP-513-1 turns away and runs out of view before disappearing without a trace.