You've undoubtedly noticed how loud it is when a professional golfer hits a ball.
It's obvious even on TV. Most people think it's the high clubhead speed that has a lot to do with it, but the sound comes more from the compression of the ball against the club.
Only a small percentage of amateurs compress the ball. This requires an accelerated swing with both hands in front of the clubhead at impact and the club body angled toward the target.
The right arm (for right-handers) plays a crucial role in delivering this downward strike. If the arms deploy too quickly or too far away from the body on the downswing, you will never achieve the "lag" effect that all pros are looking for.
This simple exercise will help you learn the proper right arm action into the shot.
Using a short or mid-iron, hold the club with your right hand only.
Place the ball between your feet.
Slowly move the club back, stopping halfway up the backswing.
As you swing at the ball, keep your right hand in front of the club head. Your hand should be level with your left leg when the club makes contact.
It will take several repetitions to get used to this one-handed swing. Do this about 50 times, then try a series of accessible two-handed swings with the same right-handed motion.