diff --git a/lib/types/thread-permission-types.js b/lib/types/thread-permission-types.js
--- a/lib/types/thread-permission-types.js
+++ b/lib/types/thread-permission-types.js
@@ -384,11 +384,6 @@
     threadPermissionFilterPrefixes.OPEN +
     threadPermissions.KNOW_OF,
 
-  // descendant_open_voiced
-  threadPermissionPropagationPrefixes.DESCENDANT +
-    threadPermissionFilterPrefixes.OPEN +
-    threadPermissions.VOICED,
-
   // visible | descendant_open_visible
   threadPermissions.VISIBLE,
   threadPermissionPropagationPrefixes.DESCENDANT +