I was watching a singles match and one of the guys had very squeaky shoes. Also, it definitely looked like he was purposely taking small dragging steps while getting back to the center after a shot. This resulted in lots of annoying noises while his opponent was getting ready to hit. It seemed very obvious to me that he was trying to distract his opponent. However, it did not seem to phase his opponent at all. What is the rule on this? is this allowed?