I don't think it's bbecause ghosts are deaf. If they were, they'd have to speak rather loudly. I figure it has to do with not spooking the entity or the person (or animal- you don't want to scare a squirel or racoon) that may be actually making the noise. If the entity doesn't know they're being "hunted" or that it can be heard or seen, then a suden booming voice interrupts it, the entity may be shocked into hiding. That would take away from the evidence. That's just hypothetical though. It could alwo be to prevent contamination of other team members sessions. For example, if Steve & Tango are investigating in one room and Jason and Grant are just down stairs, Jason can't be yelling at an entity on the first floor because his voice could carry to the upstairs recorder. I know they consider contamination a lot, so that one may not be a good example. On the other hand though, I read that you shouldn't whisper on an investigation because that could make somebody's whisper se