I heard it from one of my dads mates, and it seems plausible actually if they are so loud, and positioned in certain angles of each other.
I'd imagine it would create the type of effect seen on noise cancellation headphones, that create a reverse signal.
Since all the air is pumping, they are simply hitting each other and maybe settling the air in the middle?
I don't know exactly how it worked. Maybe someone with a bit more scientific know how could explain more, but yes, I believe it would be possible.
SOMETHING ON TOMORROWS WORLD:
I know this program is really old, but there was a feature on it a while back, about the first speakers that could transmit audio in a staight line like a laser, and for it not to wave out like standard sound does, so that basically one person could hear it perfectly fine, and someone a bit out of the range couldn't at all.
I don't know what happened with them, and I imagine because they transmitted audio only in a straight line, that you couldn't produce that much bass (not enough of a wide wave) however much the technology progressed.
Random I know, but we are in conversation about speakers