callouts can be said a lot louder and repeated if deemed necessary ("SPEED SPEED SPEED"!!)
"SPEED" by itself is an utterly meaningless call. The call should be amplified by saying if the speed seen on the PM's ASI is high or low. If the speed is low for the configuration for example and the PF's ASI reading does not agree then it points to a potentially serious discrepancy between the two ASI's.
In other words the PM says "Speed high" and presumably or at least hopefully the PF will make the necessary correction. But if the speed is not high by the view of the PF then he can say "Crap" there is something wrong with your (or mine) ASI.