When the band leaves to speak with Mangros about his harmful audio, Karana leaves her necklace (removed to prove it was protection against Mangros' audio) behind on the chair. The next scene, when the band is standing in front of Mangros, Karana has the necklace back on and she keeps it on for the rest of the episode.
When Buck kicks Yarat and sends him stumbling backward into the wall, the wall visibly flexes and bends under the impact.
Buck proves that the necklaces worn by the band are what protects them from the evil effects of their music onto others. This is proven when Katana removes hers and tries to kill Buck when the music plays. For some reason, however, this does not affect Buck, who himself is not wearing a necklace.