He is super responsive to voice, and I talk to him all the time. Heck, another quirk my spouse found was that if you say "Good Boy" in a bright tone of voice he stops dead. I didn't believe him until I tried it myself and sure enough. I've had 2 other people try saying it from the ground or on his back and then gelding just shuts down and drops his head. Rather disconcerting LOL, now we say "Niiiice" instead.
If I do not use the short dressage whip while trying to lunge him he will go out for maybe 2 circles and stop/turn and face me. Then the process starts over, with me having to talk him into going back out on the circle.
But with the short whip I can growl at him and shake the whip just slightly and keep him out on the circle.