Re: For those looking to speak their minds
There are many links that explore or report "audio beam" and "silent sound" techniques
But to actually experience one of these in the field, who can say? Well, now I can!
I was at the Oxford Valley Mall yesterday morning. It was relatively quiet, with just a little muzak playing. When I went up the escalator to the restroom area, I passed through a "sound beam" that was obviously directed at the escalator passengers on their way upstairs!
This brings me to a conclusion: sound beam technology is probably used at many choke points in commercial venues. Choke points can include escalators, stairways, elevators, etc.
However, the escalator is uniquely suited for this technology because it keeps you MOVING: you can't just stay at one place long enough to be aware of it!
So, my humble advice is make sure that when you are speaking your mind you're really speaking YOUR mind! ;-)