From Chapter 20 - Imprisonment:
"Seeing the utter gloominess on Mr. Huang-Zhong?s face, Linghu Chong felt
very sorry. He thought to himself, ?Big Brother Xiang apparently did not
want to review the fact that I have lost all my inner strength, so as
not to make them aware of my intent to ask for treatment, thus, void any
obstacles that might arise. But a real man should be as open as the day.
I can?t take advantage of him like that.? At that thought, he said,
?First Master, there?s something I must tell. The reason why I was
immune to the invisible energy attacks coming out of your zither was not
because of advanced inner strength cultivation on my part. It was really
because I have no inner strength in me, none whatsoever!?
?What did you say?? Mr. Huang-Zhong stood up, taken by surprise.
?I was injured many times and have lost all my inner strength. That?s
why the sound of your zither had no effect on me,? Linghu Chong explained."
Maybe Linghu Chong was being generous to Huang Zhong to soothe his hurt, but he specifically says that he's immune to the atack, rather than he was able to overcome the attack. In an earlier passage, the attack is described as "Once the opponent?s internal strength resonated with the zither sounds, then he would be controlled by the zither sounds involuntarily." So if LHC has strong internal energy inside him that's mostly out of his control, the energy would still "involuntarily" resonate at some point with HZ's notes. But as LHC says, his internal energy couldn't resonate, voluntarily or not, because he had none.