What is the meaning of the invalidation of the Two Testimonies for someone who listens to music, and how is that known?

Perhaps the questioner means by "disqualification of testimony for one who listens to haram (definition)" that this constitutes wickedness (fisq) which contradicts the uprightness (adalah) required for accepting someone's testimony. It is incumbent upon a Muslim to avoid listening to forbidden things, such as musical instruments. The disqualification and invalidation of testimony occur if two just witnesses confirm it before the judge. Among the matters that require the testimony of two just witnesses are impugning (tajreeh) and vindicating (ta'deel).