A vacuum tunnel was an artificial environment in which a vacuum was created.
History and specificsEdit
In the 23rd century, during a performance given by entertainers Allura and Anzar, Allura joked that she would love to hear Anzar play his budupaphone in a vacuum tunnel. The humor of the comment was that, as sound does not travel in a vacuum, the budupaphone would be completely inaudible. (TOS comic: "The Hijacked Planet")