Yelling doesn't work either. The problem is SINAD: Signal/(Noise+Distortion). Yelling amplifies the signal and the distortion and makes echos off the walls too.
When talking to a deaf person like me, first turn off other sources of sound: TV, radio, lawn mowers, chain saws - get everyone else to shut up and then just talk a little more loudly and a little more slowly maybe as well.
Hmm, I used to build military observation systems and the few things I looked at are obvious lens reflections making dots that, if you try to chase them, keep moving as you turn. With complex lens systems, you can get multiple dots. I have even seen a big spot caused by my aircraft window when flying over clouds, so the effect is not limited to a camera system - an Airbus A320 window will also do!
Canada, Norway, Azerbaijan and Venezuela sure are not complaining about oil shortages. Also, Saudi, UAE, and Iraq are making more money selling less oil from their west coast terminals and pipelines than before, so they are not complaining either.