The Silencing is the name given to a global phenomenon centered around the unexplained onstage disappearances of popular musicians worldwide.
The initial cause is Noise Beasts entering the human world through cracks in the boundaries between worlds. They are attracted to large musical performances and attack popular musicians, who are unable to defend themselves without a NOISZ.
As of NOISZ STΔRLIVHT, Beyond claims to Producer that Gaius Antiphon's plan to stop the Silencing is to sever the connection between the human world and the World of Music entirely. She states that her own plan is different - to repair the boundary between the two worlds instead.
In NOISZ re:||VERSE, "The Silencing" is the term used to describe the worldwide inability to compose music that has persisted for two weeks by the time re:||VERSE's story begins. At this point, the main character mentions that the Silencing, as a conspiracy theory, has been in circulation for over a year.