I agree...A few years back...I hiked 2 miles off the road and set up on a mountain top....Called once with a slate...heard nothing...waited 20 minutes, called again...nothing....waited 20 minutes and called....next ridge over gggggggggoooooooooobbbbbbbbbbllllllllllllllllleeee eeeeeeeeee.....I put my mouth call in...waited 10 minutes....yelped and he answered again....75 yards away....I rolled him at 30 yards....right at 7:30 am....I'm convinced that bird probably heard my first two sets of calls from the slate....but I couldn't hear him....